GLASGOW  Pope Benedict XVI arrived Thursday in Scotland, offering his strongest criticism yet of the Roman Catholic Church’s handling of the sexual abuse crisis. He said that church leaders had not been “sufficiently vigilant” or “sufficiently swift and decisive” in cracking down on abusers.

While Benedict was received graciously by Queen Elizabeth II in Edinburgh and thousands turned out for an open-air Mass in Glasgow, the visit was taking place under the dark shadow of the sexual abuse scandals, which have shaken even the faithful in nearby Ireland, in his native Germany and elsewhere in Europe.

Protests were planned by atheists and gay and human rights activists incensed by the pope’s handling of the scandals and by others opposed to the church’s stance on social issues. Centuries after the Church of England split from Rome, some Anglicans are wary of the Vatican’s recent efforts to draw traditionalists to Roman Catholicism. That the occasion for the visit is the beatification of Cardinal John Henry Newman, England’s most famous Catholic convert, has only added to their suspicions.

Ahead of the pope’s four-day visit, one of Britain’s most prominent Catholic leaders spoke about the wounds left by the church’s failures in the abuse cases.