Pier Paolo Cito, File, Associated Press
The 85-year-old pope announced Monday he would resign Feb. 28, telling a meeting of Vatican cardinals that he no longer has the physical strength for the demands of the job.

Pope Benedict XVI's suprising announcement that he will resign is being lauded by Roman Catholic leaders, scholars and laity as courageous, selfless and in the best interest of a church that represents half of the world's Christians.

The 85-year-old pope announced Monday he would resign Feb. 28, telling a meeting of Vatican cardinals that he no longer has the physical strength for the demands of the job.

"I think it is significant that instead of clinging to power, he voluntarily relinquishes it in the service of the church that he has guided so well," said Bishop John C. Wester, who heads the diocese of Salt Lake City.

In becoming the first pontiff to resign in 600 years, Pope Benedict sent a message that demands on church leaders are increasing and that his successor will face formidable challenges pastoring more than 1 billion Catholics in what he has repeatedly called an increasingly secular world that threatens the faith's stands on family and social justice.

"I think it was an extremely courageous thing to do. It now offers an example for future popes that when the burden of the office become too great they will have the model of Benedict to follow in resigning," said Larry Cunningham, a retired professor of theology at Notre Dame University.

The pope's announcement sets in motion planning for a conclave of cardinals that will convene sometime in March to elect a new pope, possibly before Easter, since the church will not have to observe the traditional periods of mourning and funeral that take place when a pope dies.

Declining health

When Benedict was elected in 2005 at age 78, he was the oldest pope chosen in nearly 300 years and was already planning to retire as head of the Congregation for the Doctrine of the Faith — the Vatican's chief orthodoxy watchdog.

He was also a top adviser to Pope John Paul II and witnessed how the declining health of the pontiff hindered his ability to lead. Benedict himself, as recently as 2010, reportedly raised the possibility of resigning if he were too old or sick to continue.

Reports on the announcement concurred that the pope has noticeably slowed down in recent years, cutting back his foreign travel and limiting his audiences. A moving platform spares him the long walk down the aisle to the altar in St. Peter's Basilica.

Still, the announcement made in Latin at the end of his remarks at a routine meeting of cardinals took many by surprise.

"All the cardinals remained shocked and were looking at each other," said Monsignor Oscar Sanchez of Mexico, who was in the room at the time of the announcement, according to the Associated Press.

Benedict emphasized that carrying out the duties of being pope requires "both strength of mind and body."

"After having repeatedly examined my conscience before God, I have come to the certainty that my strengths due to an advanced age are no longer suited" to the demands of being the pope, he told the cardinals.

"In today's world, subject to so many rapid changes and shaken by questions of deep relevance for the life of faith, in order to govern the bark (ship) of St. Peter and proclaim the Gospel, both strength of mind and body are necessary — strengths which in the last few months have deteriorated in me."

Cunningham noted that the pope made clear he was making this decision consciously, freely and explicitly — the conditions under which a pope can resign.

The last pope to resign was Pope Gregory XII, who stepped down in 1415 in a deal to end the Great Western Schism, a dispute among competing papal claimants. Three other popes have resigned in the history of the church. Pope Benedict IX stepped down in 1045 to get married; a year later Pope Greogy VI was forced to resign for bribing his way to the papacy; and in 1294 Pope Celestine V stepped down after declaring he had the right to resign and go back to his former life of solitude.

The reasons no other pope has resigned since 1415 vary. According to the Rev. Monsignor Robert Wister, a professor of church history at Seton Hall University, health reasons weren't a concern until John Paul II's suffering from Parkinson's disease hampered his ability to lead during his last years.

Others have pointed out the possibility of a schism if there were two living popes. But a Vatican spokesman, the Rev. Federico Lombardi, said such a scenario couldn't happen because a resigning pope no longer has the right to govern the church.

The Vatican said that immediately after his resignation, which will take effect at 8 p.m. Feb. 28, the retired pontiff will go to Castel Gandolfo, the papal summer retreat south of Rome, and live in a cloistered monastery.

Pope Benedict said he would serve the church for the remainder of his days "through a life dedicated to prayer."

Conclave of cardinals

While he will not take place in election of his successor, the pontiff has already had an indirect influence on who will be candidates for the papacy. In his eight years as head of the church, Pope Benedict has reportedly hand-picked 67 of the 118 members of the College of Cardinals who are eligible to elect his next successor.

Wister said the cardinals will gather in the Vatican's Sistine Chapel soon after the pontiff retires to cast ballots until a candidate receives a two-thirds majority, a procedural change made by Pope Benedict in 2007 to prevent cardinals from pushing through a candidate who had only a slim majority.

As per tradition, the ballots are burned after each voting round; black smoke that snakes out of the chimney means no pope has been chosen, while white smoke means a pope has been elected.

Wister said the pope is the Bishop of Rome and carries the authority of the ancient Apostle Peter. Technically any male within the layity or clergy of the church is a candidate for pope, but the pontiff has traditionally come from the church's cardinals who are appointed by the pope.

The speculation on Monday was that a candidate from the high growth regions of Latin America or Africa could be elected. "This may be the time to break out of Europe," Wister said, noting that the elections of Pope Benedict, a German, and his predecessor from Poland broke with the centuries-old tradition of an Italian pope.

Wister and Cunningham confidently predicted the new pope would not be from the United States because of the dominant secular power and influence the country has in the world.

The pontiff's resignation and election of a successor will take place during a richly symbolic time for Catholics, who begin their 40 days of Lent on Ash Wednesday — a solemn period of reflection that culminates with Holy Week and then Easter, on March 31, celebrating the resurrection of Jesus Christ and a new beginning.

"This historic decision comes fittingly as the church prepares to enter the season of Lent, where marked with ashes, we are reminded of our human limits and utter dependence on the grace and providence of the Lord of history," Brian Birch, president of CatholicVote.org, said in a statement.

Defender of the faith

The shy and academic Pope Benedict XVI was elected pontiff following in the footsteps of the popular and outgoing John Paul II, who served for 26 years.

Under his predecessor, the then Cardinal Joseph Ratzinger was responsible for articulating and enforcing official church teaching on highly contested issues, including homosexuality and women’s ordination, said Michele Dillon, a scholar of Catholicism and professor of sociology at the University of New Hampshire.

As pope, he tried to return the church to its historical roots that he felt were lost by a misinterpretation of the modernizing reforms of the Second Vatican Council in the early 1960s.

"He emphasized time and again the threat against the church and faith in general posed by the forces of secularism, especially in Europe where he witnessed historically Catholic countries embracing legislation extending on divorce, abortion, and gay rights," Dillon said. "But he also spoke out against economic inequality and emphasized the responsibility of highly developed countries toward disadvantaged economies and societies.”

His brief tenure was also marked by a worldwide clerical sex abuse scandal, communication gaffes that outraged Jews and Muslims alike and, more recently, a scandal over leaked documents by his own butler. Many of his stated priorities as pope also fell short: he failed to establish relations with China, heal the schism and reunite with the Orthodox Church, or reconcile with a group of breakaway, traditionalist Catholics.