Franco Origlia / Getty Images Contributor

Pope Francis waves to the crowd as he leaves at the end of the Holy Mass and Canonization Ceremony at St. Peter's Square. Sunday.

Editor's note: This story includes a correction.

ROME -- Pope Francis canonized more than 800 Catholics in Saint Peter’s Square Sunday – the largest number to be elevated to sainthood at once in the history of the Catholic Church.

The choice of some of the new saints was also striking, touching on the already-fragile relationship between Christianity and Islam.

The new saints included hundreds of laymen from the southern Italian port town of Otranto who were slain in the 15th century by the invading Ottoman Turkish army after they refused to convert to Islam.

In 1480, after conquering Constantinople – modern day Istanbul - the Ottoman Sultan Mohammed II planned to invade Rome, and Otranto became his army’s port of entrance into Italy.

The local population fought back in a week-long siege, putting up a brave but hopeless resistance. When Ottoman soldiers finally overrun the town, they were ordered to kill every man over the age of 15 who refused to convert to Islam.

More than 800 resisted, locking themselves up into the town’s Cathedral. Their ringleader, local shoemaker Antonio Primaldo, was first to be beheaded. According  to local legend, his headless body remained standing until the last of his fellow townspeople was killed.

Since then, Primaldo and his townsfolk, who chose to die rather than betray their Catholic faith, have been hailed as martyrs. Their bones and skulls – proudly on display behind glass walls in the Cathedral of Otranto – are well-known Catholic relics and a popular pilgrimage destination.

But the choice to highlight their sacrifice may put a strain on the already fragile relationship between the Catholic Church and Islam.

Ever since his election, Pope Francis has called for greater dialogue between Christianity and other religions, in particular Islam. And so far, he has acted on that promise. He washed the feet of a young Muslim woman jailed in a juvenile prison on Holy Thursday, and reached out to the many “Muslim brothers and sisters” during his first Good Friday procession.

So why risk creating yet another inter-faith row with a celebration which some in the Muslim world may be seen as a provocation?

The answer is that it wasn’t Pope Francis’ choice in the first place. The decision to canonize the hundreds of Otranto martyrs was rubber-stamped by his predecessor, Pope Benedict XVI, on Feb. 11 - the same day he announced his resignation.

Slideshow: The election of Pope Francis

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Cardinals from around the world gathered in the Vatican to elect the next leader of the Roman Catholic Church.

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It was a departing act of a pontiff that had become concerned about the mounting discrimination suffered by Christian minorities living in the Middle East in the wake of the Arab spring.

Pope Francis shares his predecessor’s concern. “By venerating the martyrs of Otranto” he said at Sunday’s canonization mass, “We ask God to protect the many Christians who in these times, and in many parts of the world, are still victims of violence”.

The Vatican’s relationship with Islam took a nosedive in 2006 when Benedict – now the Pope Emeritus - enraged Muslims by quoting the 14^th-century byzantine emperor Manuel II Palaiogolos, who said: “Show me just what Muhammad brought that was new and there you will find things only evil and inhuman, such as his command to spread by the sword the faith he preached.”

It was an uncomfortable parting gift for his successor, who now faces an uphill struggle to rekindle ties with Islam.

Related: 

• Pope condemns 'slave labor' conditions in collapsed Bangladesh factory

Franco Origlia / Getty Images

Pope Francis waves to faithful as he arrives in St. Peter's Square in the Vatican City on Wednesday. Marking the feast of St Joseph the Worker and World Labor Day, the pontiff launched an urgent appeal to Christians and men and women of goodwill worldwide to take decisive steps to end slave labor.

Pope Francis took aim at corporations Thursday with a tweet heard round the world:

While that’s not a shocking viewpoint from a former Latin American Jesuit known for his austere lifestyle, the bluntness of the message and the social-media pulpit he used to deliver it gained plenty of attention.

Asked about the tweet Thursday at a news conference, Mario Draghi, president of the European Central Bank, paused then replied cautiously: "We are...frustrated, yes certainly.”

The Twitter message came a day after Pope Francis ripped into the "slave labor" conditions at a Bangladesh factory whose collapse last week killed hundreds.  

The tweet is only the 30th penned by Francis since he became leader of the world's 1.2 billion Catholics, and was the first time he used a Twitter account followed by millions to convey so sharp a point. (Two days earlier, he tweeted benignly, "How marvelous it would be if, at the end of the day, each of us could say: today I have performed an act of charity towards others.)

But Thursday’s message is consistent with the one the Church has espoused for centuries, theologians say.

"Benedict said much the same thing in his final encyclical," said Thomas Groome, a Boston College professor of theology and religious education who has written numerous books on faith. "It's consistent teaching of the Catholic Church: The profit motive alone cannot be unbridled, cannot be uncontrolled, cannot be unchecked. It has to contribute to the common good."

Not all the faithful on Twitter were quick to see it that way. Among the responses:

"And what was the revenue generated by the Vatican last year?" 

"You big lefty."

"Terrific... you're another empty headed socialist... hell of a job, College of Cardinals."

And John MacDonald, managing director at the JMAGroup accounting firm in Oakville, Ontario, shot back: “blah blah blah... it's always the capitalist....what about self indulgent employees who never retrain or take control of their options?”

The pope’s tweet also got nearly 6,000 retweets and was “favorited” more than 2,500 times, a sign that on a day when the European Central Bank announced it would be cutting its key interest rate a quarter-point as employment in Europe still lags, some faithful appreciate an attack on corporate greed from Catholicism's top man.

“Anyone who has lived in poverty and deep poverty — people are not really enjoying being poor. They are always, every day, thinking about what could take me out of this," said John Taylor, president of the National Community Reinvestment Coalition, which helps residents of low-and moderate-income communities get access to banking services. "But they don’t have college degree, they don’t have a rich uncle. They don’t know someone who is about to give them an $80,000 job, and they don’t the contacts or the influence. Self-reliance works well when you have a lot to rely on.”

Since the global financial collapse of 2008, unemployment rates around the world have surged. In the U.S., the painfully high 7.7 percent unemployment rate is among the lowest in the developed world.

In Europe, unemployment reached 12.1 percent in March, an all-time high. In Spain, more than one in four are without a paycheck. In the Arab world, rising unemployment – largely among younger job seekers – fueled an “Arab spring” of social unrest in 2010 from Morocco to Saudi Arabia.  Since then, unemployment has continued to rise – to about 16 percent.

This global surge in joblessness has sidelined a large segment of the generation that came of age during the Great Recession. The Economist magazine recently figured that the number of young people out of work globally is nearly as big as the population of the United States.

Known for his humility in his own work, Francis has shunned many perks throughout the years. Back in his hometown of Buenos Aires, before he was elected pope, he rode city buses to get around, and lived in a plain apartment downtown as opposed to the opulent mansion he was entitled to as cardinal.

And shortly after he was elected leader of the Roman Catholic Church, he washed the feet of a dozen inmates in a juvenile detention center in a religious rite as a humble servant of the faithful.

As the pontiff’s pointed tweet made the rounds, another tweet came Thursday from someone better known for his financial opinions: Billionaire Warren Buffett joined Twitter for the first time, saying simply: "Warren is in the house."

He picked up more than 81,000 followers in an hour.

NBC's Amy Langfield contributed to this report.

Alessandra Tarantino / AP

Pope Francis waves to faithful as he is driven through the crowd in his popemobile during his weekly general audience in St. Peter Square at the Vatican, Wednesday, April 24, 2013. Writing on the banner in the background reads in Italian "We are not afraid".

ROME – More than one month since his election, Pope Francis is winning new fans and drawing big crowds to the Vatican.   

St. Peter's Square has been filled to capacity during the pope’s public events – like the Wednesday general audience and Sunday blessing. 

Vendors and shopkeepers have had swift sales of rosaries, candles, pens and even lighters carrying Francis' smiling face since his election. The demand for pope-related goods is even fueling the black market – earlier this week police in Milan seized a million items made in China carrying the image of the Pope illegally smuggled into the country.

Many Catholics, at least in Italy, have been won over by Francis’ humility. 

Alberto Pizzoli / AFP - Getty Images

Pope Francis received a rosary from a young girl as he arrives for his weekly general audience at St Peter's square on Wednesday, April 24, 2013 at the Vatican.

“He behaves like one of us, he is one of the people,” said 42-year-old Roberto Delantero, a devout Catholic and admirer of the Franciscan order. “He said he is infinitely small, just like Saint Francis called himself. It’s a nice break for the Catholic Church, which in recent years rose above the people.” 

“He is a man of the people, he doesn’t sit on a pedestal,” said Maya de Roo, a 32-year-old Dutch florist based in Rome who met Pope Francis after helping with the flowers arrangements in St. Peter’s Square for Easter Mass.

Of course, de Roo brought up a comparison to his predecessor, the now Pope Emeritus Benedict XVI.

“After the mass, he came to thank us florists and he was looking at all of us in the eyes. It was clear he was happy to be with us. He was emanating a positive energy that I never felt with Benedict.”

Osservatore Romano / Reuters

Pope Francis receives Inter Milan captain Javier Zanetti's soccer jersey during their private audience at the Vatican on Thursday, April 25.

And while Francis hails from Buenos Aires, which is almost 7,000 miles away from Rome, Italians welcomed him as one of their own overnight. (Francis joked after his election, “the cardinals found me at the end of the world.”)  

His Italian roots – his parents come from the northern Italian Piedmont region – provided an instantaneous familiarity that was missing with Benedict, who was perceived as “too German” for many in Italy.

But that hasn’t stopped Francis, who is a big soccer fan, from connecting with some of fellow Argentine transplants. He had an “emotional” hour-long audience with Inter Milan’s captain Javier Zanetti, also originally from Buenos Aires, and received an autographed jersey from Barcelona star Lionel Messi, an Argentine considered the world's best player. 

The new pope is also winning fans stateside, as many as 84 percent of U.S. Catholics view him “favorably” according to a  Pew Research Center survey conducted at the end of March. That’s compared to just 67 percent of American Catholics who viewed his predecessor Pope Benedict favorably about three months into his papacy.

Small gestures
More than ethnicity and bloodline, his humility has impressed many. Through many gestures since his election, the new pope has showed an effort to live up to the name he took in honor of Saint Francis of Assisi, a saint renowned for renouncing the life of wealth he was born into for one of poverty. 

The list is long: he boarded the shuttle bus back to the basilica from the Sistine Chapel among other cardinals on the night he was elected, refusing to take the Vatican “limo” fit for a pope. He insisted on paying the small hotel he stayed in before entering the conclave after he was elected pope.

Dmitry Lovetsky / AP

A souvenir vendor sells portraits of Pope Francis at the Vatican on March 18, 2013.

Perhaps most shockingly of all, he has refused to move into the lavish papal apartment, allegedly saying, “you can fit 300 people here!” Instead, he has chosen to sleep in a simple room in Domus Santa Martha, the same hotel-style residence he stayed in during the conclave that elected him on March 13. 

The only people who might not be so impressed by his humbleness, ironically, may be the Vatican employees. The pope announced last week that the approximately $2,000 bonus workers at the Holy See traditionally receive every time a new pope is elected must go to the poor instead.

Related links:

NBC News coverage of Pope Francis

Pope Francis: Hypocrisy 'undermines Church's credibility'

'It was a sign': Lapsed Catholics lured back by Pope Francis

Riding in style: The evolution of the popemobile

Max Rossi / Reuters

Pope Francis, shown Sunday, reaffirmed the church's official criticism of the group representing most U.S. nuns as having 'radical feminist' doctrine.

VATICAN CITY -- Pope Francis has reaffirmed the Vatican's criticism of a body that represents U.S. nuns that the Church said was tainted by "radical" feminism, dashing hopes that he might take a softer stand with the sisters.

Francis's predecessor, Benedict, decreed that the Leadership Conference of Women Religious (LCWR), a group that represents more than 80 percent of the 57,000 Catholic nuns in the United States, must change its ways, a ruling that the Vatican said on Monday still applied.

Last year, a Vatican report said the LCWR had "serious doctrinal problems" and promoted "radical feminist themes incompatible with the Catholic faith," criticizing it for taking a soft line on issues such as birth control and homosexuality.

The nuns received wide support among American Catholics, particularly on the liberal wing of the church, as LCWR leaders travelled around the United States in a bus to defend themselves against the accusations.

On Monday the group's leaders met Archbishop Gerhard Ludwig Mueller, the new head of the Vatican's doctrinal department, and Archbishop Peter Sartain of Seattle, who has been assigned by the Vatican to correct the group's perceived failings.

"Archbishop Mueller informed the (LCWR) presidency that he had recently discussed the doctrinal assessment with Pope Francis, who reaffirmed the findings of the assessment and the program of reform, " the Vatican's statement said.

The Vatican reminded the group that it would "remain under the direction of the Holy See," the statement said.

It was the nuns' first meeting with Mueller, who succeeded American Cardinal William Levada as head of the Congregation for the Doctrine of the Faith. Levada, who retired last year, oversaw the Vatican's investigation of the U.S. nuns.

A statement from the LCWR said the "conversation was open and frank" and added: "We pray that these conversations may bear fruit for the good of the Church."

In April 2012, the doctrinal department criticized the LCWR for challenging bishops and for being "silent on the right to life," saying it had failed to make the "Biblical view of family life and human sexuality" a central plank of its agenda.

The nuns supported President Barack Obama's health-care reform, part of which makes insurance coverage of birth control mandatory, while U.S. bishops opposed it.

Many nuns said the Vatican's report misunderstood their intentions and undervalued their work for social justice.

Supporters of the nuns said the women had helped the image of the church in the United States at a time when it was engulfed in scandal over sexual abuse of minors by priests. They were praised by many fellow Catholics and the media for their work with the poor and sick.

Monday's Vatican statement expressed gratitude for the "great contribution" American Catholic nuns had made in teaching and caring for the sick and poor.

Related:

Pope: Hypocrisy 'undermines church's credibility'

Lapsed Catholics lured back by Pope Francis

Pope orders church to act 'decisively' to stop abuse

Gregorio Borgia / AP

Pope Francis waves as he is driven through a crowd in St. Peter's Square prior to the start of his weekly general audience on Wednesday.

Twenty million Americans consider themselves lapsed Catholics, but Pope Francis is convincing many to test the holy waters again with his bold gestures and common touch.

After years of disenchantment with the church's hierarchy and teachings, former members of the flock say they are willing to give the Vatican a second chance under new leadership.

Dallas teacher Marilyn Rosa is one of them.

"It was a sign," Rosa, 57, said of the Argentine Jesuit's election as pontiff last month. "It was like a miracle."

Born and raised Catholic, Rosa attended parochial schools and had a church wedding for her first marriage. Over the years, she drifted away from the religion that had been such an integral part of her Puerto Rican family's life.

She questioned the relevance of church policies in the modern world. As a divorced woman, she felt cast out. The pedophile-priest scandals disgusted her.

Three years ago, she quit going to Mass and joined an evangelical church. But she didn't feel at home and she started to wonder how she could fill the void.

"The day the pope got elected, I turned on the TV and when I learned he was Latin, I went crazy at home," said Rosa.

"When they started to talk about how he lived by himself and didn't move into the archbishop's residence, how he took the bus to work, I said, 'I know God is talking to me. This is the man we needed.'"

On Palm Sunday, she and her second husband "reverted," attending services at Dallas' St. Pius X Catholic Church.

"It was packed. I had to stand up the whole time. But I felt so happy. It was like a revival," she said.

Ron Feldman

Father Peter Mussett of St. Thomas Aquinas Catholic Center in Boulder, Colo., had five people tell him they were returning to the faith in a week because of Pope Francis.

Rosa has kept going to back to St. Pius, encouraged by what she's seen of the pope: from the simple white robe he wears to his rejection of the opulent papal apartment in favor of a spartan guest house.

"He's not letting himself be controlled by the rest of the church," Rosa said. "He's his own man."

Embrace of poor, emphasis on service
It's unknown how many others have joined Rosa around the country and globe and the vast majority of lapsed Catholics have not been enticed back. In the U.S., that's a huge pool of potential "new" members for an institution challenged by secularism and rival religions.

A 2009 report by the Pew Forum on Religion and Public Life estimated one in 10 adults in the U.S. was raised Catholic but has broken with the church. Its teachings on abortion, homosexuality, birth control and treatment of women were often cited as reasons.

Pope Francis hasn't given any hint of radical change on those issues, but his man-of-the-people persona is appealing to some of the unfaithful.

Tom Peterson, president of Catholics Come Home, which airs ads aimed at the lapsed, said his website traffic tripled the day of the election, adding several thousand visitors. It's been double ever since.

Some interest could stem from the hubbub surrounding the selection of any pontiff, but Peterson thinks Francis' "love for the poor and his humility is exciting people to a great extent."

Father Peter Mussett, pastor of the St. Thomas Aquinas Catholic Center, which serves the University of Colorado at Boulder, agrees.

Slideshow: Pope Francis: His life before the papacy

Marcos Brindicci / Reuters

Cardinal Jorge Bergoglio of Argentina was elected to lead the Catholic Church following the resignation of Pope Benedict XVI. 

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"I had five people in a week who were saying, 'Pope Francis has inspired me to return to my faith,'" he said. "It's pretty remarkable."

Brian O'Neill, 48, an Irish-American cop from Washington State, went to Catholic elementary school and a Jesuit high school but hasn't practiced since graduating from a secular college. He says that could change soon.

The Vatican's stance on social issues, along with the gilded lifestyle of some higher-ups previously drove O'Neill away. Francis' embrace of the poor and his background as a service-minded Jesuit might bring the father of two back.

"I was shocked and amazed when he started doing those things -- you know, 'No Popemobile for me,'" said O'Neill, who wrote a column for his local newspaper about possibly returning to Catholicism.

He said that while Francis' views on church teachings might still be far from his own, his election heralds change.

"When the church says that's the guy we're going to put on St. Peter's throne, that says enough about where the church wants to go," O'Neill said. "Will I go back? I'm planning on it -- if I can find a good service."

'He's another retro pope'
Last weekend, when he was formally installed as bishop of Rome, the pope used the opportunity to appeal to defectors, urging them to come back to the fold.

The News Tribune (Tacoma)

Brian O'Neill, a cop and father of two from Washington state, is a lapsed Catholic who is considering returning to the church because of Pope Francis.

It will take more than an invitation for Kathy Budreski, though. The 70-year-old left Catholicism after the abuse scandal and has been attending a Unitarian church in Cape Cod.

She was heartened to see the cardinals pick a pope from South America, and loved seeing Francis hug a little boy with cerebral palsy after Easter Mass but says he's not a progressive.

"He has a big heart and he loves the poor people, but he's not going to do anything to change the stance of the church on birth control and gay rights," she said.

"I don't see him as a mover and shaker. He has some wonderful qualities but he's another retro pope."

Slideshow: The election of Pope Francis

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Cardinals from around the world gathered in the Vatican to elect the next leader of the Roman Catholic Church.

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Related:

Sex-abuse crisis: Experts draft to-do list for Pope Francis

'Peace to the whole world': Pope urges unity in Easter Sunday address

Pope chooses simple residence over regal papal apartment

Full coverage of Pope Francis from NBC News

Franco Origlia / Getty Images

Pope Francis said that the church must "act decisively" to stop child sexual abuse by priests.

VATICAN CITY -- Pope Francis wants the Catholic Church to "act decisively" to root out sexual abuse of children by priests and ensure the perpetrators are punished, the Vatican said on Friday.

Francis, in a meeting with the Holy See's doctrinal chief, Archbishop Gerhard Mueller, had declared that combating sexual abuse was important "for the Church and its credibility", a statement said.

Francis inherited a Church mired in problems and a major scandal over priestly abuse of children. It was believed to be the first time he had taken up the issue of sex abuse with a senior member of his staff since his election on March 13.

Mueller is head of the Congregation for the Doctrine of the Faith, the Vatican department which includes the office of the "promoter of justice", or sex crimes prosecutor, which investigates cases of sexual abuse and decides if priests are to be defrocked.

Slideshow: Pope Francis: His life before the papacy

Marcos Brindicci / Reuters

Cardinal Jorge Bergoglio of Argentina was elected to lead the Catholic Church following the resignation of Pope Benedict XVI. 

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Francis said the department should continue to "act decisively as far as cases of sexual abuse are concerned, promoting, above all, measures to protect minors, help for those who have suffered such violence in the past (and) the necessary procedures against those who are guilty," a statement said.

It said the pope wanted Catholic bishops around the world to promote and put into place "directives in this matter which is so important for the witness of the Church and its credibility".

A victims' group, the Survivors Network of those Abused by Priests (SNAP) said the statement did not go far enough and criticized it for saying that the Church's stance against sexual abuse was "a continuation" of the line wanted by Francis' predecessor, Pope Benedict.

"Action, not discussion, is needed," SNAP said in a statement.

"We can't confuse words with actions. When we do, we hurt kids. We must insist on new tangible action that helps vulnerable children protect their bodies, not old vague pledges that help a widely-discredited institution protect its reputation," it said.

SNAP and other victims groups say there is much still to be discovered about how the Church behaved in the past and want more bishops who were aware of abuse to be held responsible.

The Catholic Church's crisis began in Boston in 2002 when media began reporting how cases of abuse were systematically covered up and abusive priests shuttled from parish to parish instead of being defrocked and handed over to civil authorities.

Since then, the Catholic Church in many countries has set up new guidelines to deal with cases of past abuse, prevent new cases, report abuse to police, and stop potential abusers from entering the priesthood in the first place.

Related:

Pontiff urges peace in first Easter address

Pope Francis washes feet of detainees

Full Vatican coverage from NBC News

This story was originally published on Fri Apr 5, 2013 8:28 AM EDT

Pope Francis called for worldwide efforts towards peace in his first Easter Sunday address, urging leaders to find diplomatic solutions in Syria and North Korea.

In his first "Urbi et Orbi" message from the balcony of St Peter’s Basilica, he also asked for reconciliation between Israelis and Palestinians solutions to conflicts in several African countries.

Earlier this month, the former Cardinal Jorge Bergoglio of Argentina stood on the same balcony after being elected as the first pope from the Americas in more than 1,300 years.

Francis, who has emphasized a humbler style to the papacy, said: "Peace to the whole world, torn apart by violence linked to drug trafficking and by the iniquitous exploitation of natural resources! Peace to this our Earth! May the risen Jesus bring comfort to the victims of natural disasters and make us responsible guardians of creation.”

Christopher Furlong / Getty Images

Pope Francis greets the faithful prior to his first 'Urbi et Orbi' blessing from the balcony of St. Peter's Basilica, Sunday.

He added: “Peace in Iraq, that every act of violence may end, and above all for dear Syria, for its people torn by conflict and for the many refugees who await help and comfort.  How much blood has been shed!  And how much suffering must there still be before a political solution to the crisis will be found?”

Slideshow: The election of Pope Francis

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Cardinals from around the world gathered in the Vatican to elect the next leader of the Roman Catholic Church.

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Earlier, the pontiff strode onto a flower-bedecked esplanade facing St Peter’s Square, into which tens of thousands of faithful had gathered from early Sunday, to lead the traditional open-air Mass.

Francis bowed his head in reflection as the Gospel was sung in Latin, The Associated Press reported, recounting what Christians believe is the central mystery of their faith — the resurrection of Jesus after this death by crucifixion.

"Let the risen Jesus enter your life,” the pope told worshippers before the service via his Twitter account. "He will receive you with open arms."

The Associated Press contributed to this report.

Related: The evolution of the Popemobile

This story was originally published on Sun Mar 31, 2013 5:08 AM EDT

Angelo Carconi / AP

Pope Francis is driven through the crowd in in St. Peter's Square for his inaugural Mass at the Vatican on Tuesday, Mar. 19, 2013. Francis took his name from Francis of Assisi, who was known for his concern for the poor and downtrodden, and for a 13th century encounter with the Sultan of Egypt.

Catholics and Muslims have come a long way since the Crusades, but during the tenure of Pope Benedict XVI, relations between the world’s two largest religions hit the skids.

So it was with relief and renewed optimism that prominent Muslims and interfaith advocates cheered the newly anointed Pope Francis.

"We are hoping for better relations with the Vatican after the election of the new pope," Mahmud Azab, adviser for inter-faith affairs at Al-Azhar, Sunni Islam's highest seat of learning in Cairo, told AFP. "We congratulate the Church of St. Peter and all Catholics around the world."

From the start, Benedict put less energy in reaching out to other religions than his predecessor, Pope John Paul II, who blazed the trail for Catholic relations with Muslims and other religions through his tireless travels and scores of meetings and prayer with imams around the world.

Under John Paul, the Vatican launched the World Day of Prayer for Peace in 1986, which was at first a hard sell for prominent Muslims, said Father Thomas Michel, who has a PhD in Islamic studies and headed John Paul’s office for Islam for 13 years.

"By the second one [World Day of Prayer for Peace in 1993] Muslims could see he didn’t have any other agenda — that he wasn’t going to get them all together and convince them to become Christians," said Michel, now a professor of Christian-Muslim relations at Georgetown University.

"By the time of the third, in 2002, there were so many leaders of Muslims organizations there wasn’t room for them on the podium… I don’t think Muslims changed so much, but what changed was the level of trust."

Mohammed brought 'evil and inhuman'
But when Benedict gave a controversial speech at the University of Regensburg in Germany in 2006 — a little more than a year after his installation as pope — he sparked fury across the Muslim world by quoting a Byzantine Emperor as saying, "show me just what Mohammed brought that was new and there you will find things only evil and inhuman."

Channi Anand / AP file

Muslim protestors rally in Jammu, India on Sept. 15, 2006 after Pope Benedict XVI made a controversial speech at the University of Regensburg in Germany.

In response to the pope's comments — though some argued they had been misunderstood — 138 leading Muslim scholars from around the world signed an open letter of protest to Benedict. In some countries there were protests and attacks on churches.

"It was a very strained period of the relationship," said John Esposito, professor of International Affairs and Islamic Studies at Georgetown University.

The Vatican took measures to patch up the fallout from Regensburg speech — which Vatican officials reportedly called "the accident." 

They held formal meetings with the Muslim leaders who had launched a "common word" initiative emphasizing the shared principles at the core of Christian and Islamic scriptures.

In October 2006, Benedict traveled to Turkey, making a symbolic visit to the ornate Blue Mosque in Instanbul where he emphasized his desire for reconciliation between Muslims and Christians.

And in 2009, Benedict traveled to Jordan and visited the site where Jesus was baptized, emphasizing the "common history" of Christianity and Islam. Even so, he stopped short of praying with his Muslim hosts in a mosque, or taking his shoes off to enter the prayer hall.

Dialogue resumed, but the relationship remained cool.

There are some early signs that Pope Francis could pick up where Pope John Paul II left off.

Reports from Argentina citing local Muslim leaders suggest that Francis — formerly Cardinal Jorge Bergoglio, the Archbishop of Buenos Aires — was a friend to the Muslim community.

One report out of the country said that in 2006 Bergoglio spoke out against the Regensburg speech, according to the Daily Telegraph of London.

Quick response to Francis
"Pope Benedict's statements don't reflect my own opinions," he said in a local press interview, according to the report. "These statements will serve to destroy in 20 seconds the careful construction of a relationship with Islam that Pope John Paul II built over the last twenty years."

That report has not been confirmed by NBC News.

But a lot of Muslim optimism about Francis is based simply on hunches about his character.

The initial impression of the pope — as a man who values simplicity, openness, and the ability to connect with all people — is appealing to Muslims, said Esposito.

Slideshow: The election of Pope Francis

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Cardinals from around the world gathered in the Vatican to elect the next leader of the Roman Catholic Church.

Launch slideshow

For the new pope’s installation ceremony, he noted: "They went out of their way to talk about how people of all major faiths are invited. From the other side, it’s interesting to see how quick Muslims were… to say how they look forward to working with him."

He referred to public statements issued by prominent imams as well as larger Muslim civil rights groups including the Council on American Islamic Relations and the Muslim Public Affairs Council.

Michel saw the same optimism about Pope Francis in a flood of email from Muslims.

"They are so happy and looking forward to working with him," he said. "He’s coming in as every pope does with a real fund of good will and they are really hoping that he will be someone he can work with."

Building trust and influence
If Francis establishes a relationship of trust with Muslims, it could have impact beyond just warm and fuzzy feelings, some observers believe.

A pope with a new approach could be important in a Muslim-majority country like Pakistan, where minority Christians -- most of them Catholics -- suffer persecution, says Jeff Siddique, a Muslim-American in Seattle who was born in Pakistan.

"If (Pope Francis) can build a relationship with the leadership in Pakistan, he may be able to convince them that protecting the Christians in Pakistan is a good thing to do," he said.

Likewise, he may be able to restart discussions with Al-Azhar University in Egypt, which cut off dialogue with the Vatican in 2011 after Benedict called for greater protections for non-Muslims after a suicide bomber attacked a church in Egypt, killing 23 people. Al-Azhar cut ties over what it said was Benedict’s "repeated treatment of Islam in a negative way."

To have an influence across religions requires a foundation of trust, said Michel.

"When they trust each other they can speak freely," he said. "If people come on as scolds or know-it-alls, they get their backs up and won’t accept it."

For some seeking clues about the pontiff’s position on Christian-Muslim relations, his choice of Francis — after Francis of Assisi — has significance beyond his emphasis on simplicity and concern for the poor and downtrodden.

A 13th century story describes how St. Francis left the camp of the crusaders who were attacking the walled Egyptian city of Damietta, and dared to cross enemy lines to meet with Malik al-Kamil, the sultan of Egypt. He risked being killed, but instead, he had a fruitful conversation with the Muslim leader and left unharmed.

The encounter is played up in newer biographies as a pivotal moment of engagement between the two religions.

"We’re seeing the church interpret Francis in modern times as a bridge," said Paul Moses, author of "The Saint and the Sultan," a 2009 book which explores the encounter. "To Muslims ears, the choice of Francis for a name should sound good," he told Religion News Service.

Did Francis choose this name as an overture to Muslims?

"I’d say that it’s pushing it to say this was a factor," said Michel. Nonetheless, he said other signs favor improving ties — from both sides of the divide.

"I get the feeling of 'let's start over, let's start a new chapter. The last one was bumpy'."

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