Pope Benedict XVI has praised the UK as a "force for good" as thousands of people turned out to greet him on the first day of his historic visit.
But he also delivered a warning about "aggressive forms of secularism", urging the nation not to lose its traditional values as it "strives to be a modern and multicultural society".
The first state visit to the UK by a pope came amid renewed anger at the worldwide child abuse scandal that has engulfed the Roman Catholic Church and dogged the Pope's own religious career.
As he flew to Scotland, the Pope spoke of his "sadness" over his Church's handling of child abuse scandals, saying that abusive priests had not been dealt with decisively or quickly enough.
The Pope's comments, to reporters on board his plane, marked his most thorough admission to date of failings in the way the sex abuse scandal was handled.
But despite the controversy, his followers turned out in large numbers in Scotland, with an estimated 65,000 at Thursday night's mass in Glasgow, where babies were passed to him to be blessed as he arrived in the Popemobile. Lothian and Borders Police estimated that a total of 125,000 people had lined the streets for the earlier procession along Edinburgh's Princes Street.
After he was officially welcomed by the Queen at the Palace of Holyroodhouse in Edinburgh, the Pope spoke of the UK's important place in history, saying: "Your forefathers' respect for truth and justice, for mercy and charity, come to you from a faith that remains a mighty force for good in your kingdom, to the great benefit of Christians and non-Christians alike."
The Glasgow crowd had been warmed up by Britain's Got Talent star Susan Boyle who got a huge cheer when she took to the stage wearing a long black coat and heels, before singing the tune that catapulted her to fame, I Dreamed A Dream from the hit musical Les Miserables.
The leader of Scotland's Catholics Cardinal Keith O'Brien expressed delight with the turnout in Edinburgh, saying: "Along Princes Street I really felt so proud. You could look to one side and see the backcloth of the castle and the ramparts and so on, and on the other side a sea of faces welcoming Pope Benedict XVI to our country."
But not everyone was welcoming - around 20 protesters gathered at the designated demonstration, their complaints ranging from abusive priests to the Pope's stance on contraception and homosexuality. Among the dissenting voices was the Reverend Ian Paisley, now Lord Bannside, who mounted a similar protest in Liverpool in 1982 for the visit of Pope John Paul II. Dr Paisley criticised the fact that the visit was not discussed in the House of Commons, adding that the "whole thing is nonsense".