Christian and political leaders in the UK have paid tribute to Pope Benedict XVI, after the pontiff's unexpected decision to resign on health grounds.
Cardinal Keith O'Brien, leader of the Roman Catholic Church in Scotland, said he was "saddened" by the Pope's resignation, announced on Monday.
The Archbishop of Canterbury, Justin Welby, praised his "remarkable and creative theological mind".
Prime Minister David Cameron said the Pope would be missed by millions.
Pope Benedict XVI will step down at 19:00 GMT on 28 February.
'Prayer and reflection'
Cardinal O'Brien - who will retire as a Catholic bishop in March - will remain a Cardinal Elector and will shortly travel to Rome to participate in the conclave, the process to elect the next pontiff.
He said: "I was shocked and saddened to hear of the decision by Pope Benedict XVI to resign.
"I know that his decision will have been considered most carefully and that it has come after much prayer and reflection."
Cardinal Sean Brady, Roman Catholic Primate of All Ireland, said Pope Benedict's resignation showed his "typical humility, courage and love for the Church".
He went on: "[Pope Benedict] has clearly come to the view that The Lord now wants him to use his remaining physical and spiritual energies by serving the Church in prayer.
"I think this is a profound act of humility, a conscientious and responsible decision to hand over the ministry of the successor of St Peter in a time of great challenge for the a church and for faith in the modern world."
Cardinal O'Brien and Cardinal Brady will both vote in the forthcoming conclave.
Britain's other Cardinal, 80-year-old Cormac Murphy-O'Connor, will take part in discussions by cardinals to elect the Pope's successor but will not be eligible to cast a vote because of his age.
Speaking to BBC News, Cardinal Murphy-O'Connor said he was "surprised but not shocked" by the announcement, "given his age, his weakness and his health".
The Archbishop of Westminster, Vincent Nichols, the head of the Roman Catholic Church in England and Wales, saluted the Pope's decision.
He said it had been made with "great courage and characteristic clarity of mind".
"The Holy Father recognises the challenges facing the Church and that 'strength of mind and body are necessary' for his tasks of governing the Church and proclaiming the Gospel.
"I ask people of faith to keep Pope Benedict in their prayers."
'Insight and courage'
In 2011, Pope Benedict set up the Ordinariate, a place within the Catholic Church for former Anglicans in the UK.
The group's spokesman, Father James Bradley, told BBC News the pontiff's time "has been one of surprises... which has continued to astonish the Church".
"He welcomed Anglicans into the Church through the establishment of the Personal Ordinariate which has been a significant landmark in the life of the Church," Fr Bradley said.
Tributes from among the Anglican community were led by the newly enthroned Archbishop Welby, who said the pontiff had held office with "great dignity, insight and courage".
He continued: "I speak not only for myself... but for Anglicans around the world, in giving thanks to God for a priestly life utterly dedicated, in word and deed, in prayer and in costly service, to following Christ.
"We who belong to other Christian families gladly acknowledge the importance of this witness and join with our Roman Catholic brothers and sisters in thanking God for the inspiration and challenge of Pope Benedict's ministry."
Speaking for the Jewish faith, Chief Rabbi Lord Sacks said he found Pope Benedict to be "a man of gentleness, of quiet and of calm... who carried with him an aura of grace and wisdom".
Meanwhile, the prime minister offered his "best wishes to Pope Benedict" who he said would be "missed as a spiritual leader to millions".
Mr Cameron said the Pope "worked tirelessly to strengthen Britain's relations with the Holy See". He added: "His visit to Britain in 2010 is remembered with great respect and affection."
Labour Party leader Ed Miliband described Pope Benedict's choice to step down as "a brave one [which] he will not have reached lightly".
He continued: "The choice of a successor is clearly an important one for the Catholic Church. Our thoughts are with those who must make such a critical decision on behalf of millions around the world."
Among the secular world however, Pope Benedict's pontificate has been criticised as a time when the Vatican has become "despised and resented" throughout the world.
Terry Sanderson, president of the National Secular Society, said: "He has played a major role in reducing the Catholic Church's popularity and its authority.
"Catholics have deserted the Church at an increasing rate, repelled by the inhumanity of [his] unbending adherence to what are perceived as cruel doctrines."