Pope Francis, the first man in the modern era from outside Europe to lead the Roman Catholic Church, prizes compassion, humility and simplicity — so much that he gave up his chauffeur in Argentina and took the bus to work.

He is the first pope to be a member of the Society of Jesus, a Catholic order founded in the 16th century by St. Ignatius Loyola. Its  members, known as Jesuits, take a vow of poverty and are known for their work among the poor and their scholarship.

“A man who calmly stands for what’s right and just,” Cardinal Edward Egan, the archibishop emeritus of New York, told NBC News. “A man of great compassion for the poor. That is what they point to first and foremost.”

During an economic crisis that gripped his home country over the last decade, Francis, then Cardinal Jorge Mario Bergoglio, asserted himself as a champion of the least fortunate and a defender of social justice.

“We live in the most unequal part of the world, which has grown the most yet reduced misery the least,” Bergoglio told Latin American bishops in 2007, according a recent profile in the National Catholic Reporter. “The unjust distribution of goods persists, creating a situation of social sin that cries out to Heaven and limits the possibilities of a fuller life for so many of our brothers.”

The new pope is known to be conservative on social issues. He has opposed abortion and gay marriage, and in 2010 he drew the ire of Argentina’s president when he said that gay adoption was a form of discrimination against children.

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Argentina in 2010 became the first country in Latin America to legalize gay marriage. During the debate that preceded the change, Bergoglio called the bill “a plan to destroy God’s plan.”

“This is no mere legislative bill,” he said. “It is a move by the father of lies to confuse and deceive the children of God.”

Argentine President Cristina Fernandez de Kirchner shot back that the then-cardinal was speaking in terms “really reminiscent of the times of the Inquisition.”

As archbishop, Bergoglio had the option to live in a palace but chose a simple apartment, according to the National Catholic Reporter. He gave up a limousine for the bus, and cooks his own meals.

In the first act of his papacy, he chose the name Francis, becoming the namesake of St. Francis of Assisi, who gave up his riches and chose a life of poverty and prayer.

He was born in Buenos Aires on Dec. 17, 1936, his father an Italian railway worker. He was elevated to cardinal in 2001 by Pope John Paul II.

At 76, he had been considered by some observers too old for the job — particularly following Benedict, who said that at 85 he was no longer healthy enough to lead the church. Francis has only one lung, the other removed because of an infection when he was a teenager.

Still, Egan said: “I can assure you that he is not feeble in any way.”

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His official biographer has said that Francis has both keen political instincts and self-effacing humility, and that he would encourage a kind of shoe-leather evangelism within the church. He is known to walk the streets of Buenos Aires to talk to the people.

He told priests in Argentina last year: “Jesus teaches us another way: Go out. Go out and share your testimony, go out and interact with your brothers, go out and share, go out and ask. Become the word in body as well as spirit.”

Perhaps helping him overcome the traditional reluctance to elect a Jesuit pope, he fell out of favor among some Jesuits in Argentina after he was elected to the title of Jesuit provincial in 1973.

Argentina was ruled in the late 1970s by a brutal military dictatorship, and many Jesuits were drawn to a progressive activist movement within the church known as liberation theology. Church leaders backed the dictatorship publicly, and Bergoglio discouraged priests from political activism.

Two of his Jesuit priests who followed the liberation theology movement were kidnapped from the slums by the military regime in 1976. Bergoglio personally appealed to the dictator, Jorge Videla, and had them freed. One of the priests later accused Bergoglio of effectively handing them over to the death squads in the first place.

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. 

Launch slideshow

Bergoglio told his biographer, Sergio Rubin, that he often hid people on church property during the regime years and once gave his own identity papers to a man to help him get out of the country.

He later was sent to a school in northern Argentina to teach high school chemistry, an assignment seen as a type of exile, before the archbishop of Buenos Aires recalled him to be his auxiliary bishop.

“He’s a strong man, a man who can put up with criticism,” said George Weigel, NBC News’ Vatican analyst. “Cardinal Bergoglio put up with a lot of criticism from his brother Jesuits for many years.”

Francis earned a degree in chemistry and was ordained a priest in December 1969. He was named archbishop of Buenos Aires in 1998.

He was said to be the runner-up the last time cardinals met to choose a pope. An anonymous account of the 2005 conclave said that he had the support of some of the more liberal cardinals before giving up the fight and telling his backers to vote for Cardinal Joseph Ratzinger, who became Benedict XVI.

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The account was attributed to a cardinal who leaked his diary to an Italian publication. It said that Francis, then Bergoglio, amassed 40 votes, more than half of what he would have needed for election, but still trailed Benedict after three ballots. His candidacy faltered on the fourth ballot, the diary said.

As Bergoglio cast his ballot beneath Michelangelo’s “Last Judgment,” the account said: “He had his face fixed on the image of Christ judging the souls at the end of time. A suffering face that implored: God, don’t to this to me.” The cardinal later declined to comment on the account.

By choosing a name no pope had chosen before, he may be signaling an era of rebirth for a church troubled by corruption and a sexual abuse crisis.

“We have to avoid the spiritual sickness of a self-referential church,” the new pope said before the conclave, according to the National Catholic Reporter. “It’s true that when you get out into the street, as happens to every man and woman, there can be accidents. However, if the church remains closed in on itself, self-referential, it gets old. Between a church that suffers accidents in the street, and a church that’s sick because it's self-referential, I have no doubts about preferring the former.”

The Associated Press contributed to this report.