VATICAN CITY — Benedict XVI always cast himself as the reluctant pope, a shy bookworm who preferred solitary walks in the Alps to the public glare and the majesty of Vatican pageantry. And on Monday, the Vatican announced that the leader of the world’s billion Roman Catholics was stepping down — the first pontiff to do so since 1415.

The German theologian, whose mission was to reawaken Christianity in a secularized Europe, grew increasingly frail as he shouldered the monumental task of purging the Catholic world of a sex abuse scandal that festered under John Paul II and exploded during his reign into the church’s biggest crisis in decades, if not centuries.

More recently, he bore the painful burden of betrayal by one of his closest aides: Benedict’s own butler was convicted by a Vatican court of stealing the pontiff’s personal papers and giving them to a journalist, one of the gravest breaches of papal security in modern times.

All the while, Benedict pursued his single-minded vision to rekindle faith in a world which, he frequently lamented, seemed to think it could do without God.

“In vast areas of the world today, there is a strange forgetfulness of God,” he told 1 million young people gathered on a vast field for his first foreign trip as pope, World Youth Day in Cologne, Germany in 2005. “It seems as if everything would be just the same even without Him.”

With some decisive, often controversial moves, Benedict tried to remind Europe of its Christian heritage and set the Catholic Church on a conservative, tradition-minded path that often alienated progressives and thrilled conservatives.

Yet his papacy will be forever intertwined with the sex abuse scandal.

Over the course of just a few months in 2010, thousands of people in Europe, Australia, South America and beyond came forward with reports of priests who raped and molested them as children, and bishops who covered up the crimes.

Documents revealed that the Vatican knew well of the problem yet turned a blind eye for decades, at times rebuffing bishops who tried to do the right thing.

Benedict had firsthand knowledge of the scope of the problem since his old office, the Congregation for the Doctrine of the Faith which he had headed since 1982, was responsible for dealing with abuse cases.

He met with victims across the globe, wept with them and prayed with them. He promised that the church must “do everything possible” to ensure such crimes never happen again. The Vatican updated its legal code to extend the statute of limitations for cases and told bishops’ conferences around the world to come up with guidelines to prevent abuse.

But Benedict never admitted any personal or Vatican failure. Much to the dismay of victims, he never took action against bishops who ignored or covered up the abuse of their priests or moved known pedophiles to new posts where they abused again.