Cardinal Joseph Ratzinger, long Pope John Paul II's right-hand man, watched that Pope's long decline and the paralysis it caused at the top in the Vatican, the intrigues and the pursuit of agendas. Elected John Paul's successor in 2005 at 78, he has clearly decided not to condemn the church to the same hiatus, becoming the first Pope to resign in 598 years, though the 10th overall. It is a brave and intelligent decision, in keeping with the integrity and thoughtfulness that has marked his papacy - along with some striking flaws. Speaking in Latin, he told a meeting of cardinals of his decision on Monday, saying that he had repeatedly examined his conscience before "coming to the certainty that my strengths, due to an advanced age, are no longer suited to an adequate exercise of the Petrine ministry." Today's world, subject to rapid changes and shaken by questions of deep relevance to the life of faith, demanded a strength of mind and body that he had lost in the past few months. He leaves a church facing the same crises and challenges it faced at his election, and some - such as clergy sexual abuse and relations with Islam - have clearly become much sharper over the past eight years. Debate about his legacy begins now. If he has been a less heroic Pope than his predecessor, who is in the process of being made a saint, he has in some ways been better balanced. He has been more introverted both in his personality and his public concerns, involving himself less with geopolitics and more with the life of the church, where he was a staunch advocate of traditional faith and practice. His public teaching has been hailed, particularly his first encyclical, Deus Caritas Est, on love, but his tenure was wracked by controversy - often self-inflicted. Quoting a dismissive remark about Islam by an emperor in Constantinople centuries before during a speech at Regensburg in 2008 led to riots across the Islamic world, including the usual church-burnings and the murder of a nun. Other incidents included downplaying the negative effects of colonisation on a visit to Latin Americans, suggesting on a trip to Africa that condoms made AIDS worse, offending Jews by reviving a Mass that prayed for their conversion, and trying to reconcile with the ultra-traditionalist and dissident Society of St Pius X who included a Holocaust denier. Last year's Vatileaks scandal, for which his butler was jailed, showed a church in disarray. But the crisis that really defined his papacy was clergy sexual abuse, in which he was even caught up personally over allegations that he was soft on a molester while he was Archbishop of Munich. His supporters say this criticism is unfair, that he understood the issue far better than John Paul II and moved far more strongly to tackle it, losing internal power struggles to do more when he was head of the Congregation of the Doctrine of the Faith. This is true but not saying a great deal, given his predecessor's notorious blinkers on the issue. Critics say the Vatican is still far from understanding how damaging abuse has been and that its response has been inadequate. As Peter Johnstone, head of Catholics for Renewal, told the Victorian inquiry into how the churches handle sex abuse last month, the Pope apologised to victims of abuse for the abuse itself, but never for how the church protected and promoted abusers and concealed their actions. The cardinals who elected him in 2005 evidently agreed with his estimate that the most serious crisis facing Catholicism was the aggressive secularism in Europe - the "culture of death" - and a declining church. This challenge is as strong as ever, compounded by the faithful's disenchantment over abuse. When the cardinals under 80 gather in Rome to elect his successor, what they see as the most important and urgent challenges will determine their choice. Total votes: 9237.