Pope Benedict XVI to resign this month

Updated at 11:30 a.m. Eastern

Pope Benedict XVI announced Monday that he would resign his position as the head of the Roman Catholic Church on February 28, shocking the Christian world and even many close to him.

Benedict, 85, announced his decision in Latin during a meeting of Vatican cardinals Monday morning, explaining that because of his advanced age and diminishing strength, he didn't feel he could carry on the job.

In his remarks to the cardinals, Benedict said his age and health left him with a level of energy, "no longer suited to an adequate exercise of the Petrine ministry." The Petrine ministry is the Vatican's official description of the office of the pontiff.

When he became pope at age 78, Benedict XVI was already the oldest pontiff elected in nearly 300 years. He's now 85, and in recent years he has slowed down significantly, cutting back his foreign travel and limiting his audiences.

The pope now travels to the altar in St. Peter's Basilica on a moving platform to spare him the 100-yard walk down the aisle. Occasionally he uses a cane. Late last year, people who were spending time with the pontiff emerged saying they found him weak and too tired to engage with what they were saying.

The Vatican stressed on Monday that no specific medical condition prompted Benedict's decision to become the first pontiff to resign in 600 years.

The pope's brother, Georg Ratzinger, told a news agency in Germany that the pontiff had been advised by his doctor not to take any more transatlantic trips and had been considering stepping down for months.

Talking from his home in Regensburg to the news agency dpa, Georg Ratzinger said his brother was having increasing difficulty walking and that his resignation was part of a "natural process."

"His age is weighing on him," the 89-year-old said of his 85-year-old brother. "At this age my brother wants more rest."

The 265th Pontiff, Benedict will be the first leader of the Church to step down voluntarily in almost six centuries. He has led the Church since 2005 through a tumultuous time that has seen him criticized for his handling of the scandal related to years of sexual abuse of young parishioners by priests and other clergy, and senior church officials' alleged moves to hide those actions.

Benedict has also had to deal with the fallout of a traitor in his own ranks -- his butler was convicted in 2012 (video) of stealing personal documents from Benedict's living quarters and leaking them to the media.

Benedict's decision sets the stage for a conclave to elect a new pope before the end of March. Vatican communications advisor Greg Burke told "CBS This Morning" that the pontiff's sudden departure doesn't leave a lot of time for Church officials to pick a replacement if they want the post filled before Easter, but he also noted that there won't be the usual delay of nine days mourning for a pope who dies in office.

"We certainly hope to have a new pope by Easter," said Burke.

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Burke said he only found out about the pope's decision a couple hours before Benedict announced it to the cardinals.

"It was a surprise, but maybe not a shock," said Burke, who had worried about the aging pontiff's health increasingly in recent weeks. "I was always very nervous when I saw him going up and down steps," added Burke, noting that Benedict had problems with at least one of his knees. He said the pontiff did not, however, have any immediate, grave medical condition that he was aware of.

New York Cardinal Timothy Dolan said electing a new pope would be all new to him since he's still learning what it means to be archbishop. At a news conference Monday, Dolan quipped he was "still writing thank-you notes from when I was made a cardinal" last year.

As cardinal, Dolan will be part of the College of Cardinals electing a new pope. In replying to questions, he said it would be "highly improbable" for him to be considered for the papacy.

The following is a transcription of part of the remarks Pope Benedict made in Latin to his cardinals on Monday morning, which was released to the media by the Vatican (Click here to read the full text):

"I have come to the certainty that my strengths, due to an advanced age, are no longer suited to an adequate exercise of the Petrine ministry.

I am well aware that this ministry, due to its essential spiritual nature, must be carried out not only with words and deeds, but no less with prayer and suffering.

However, 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 of Saint Peter and proclaim the Gospel, both strength of mind and body are necessary, strength which in the last few months, has deteriorated in me to the extent that I have had to recognize my incapacity to adequately fulfill the ministry entrusted to me."