In his remarks to the 600,000-strong crowd, the pope issued his strongest denunciation of religious intolerance yet in Cuba.
He referred to the biblical account of how people persecuted by the Babylonian king "preferred to face death by fire rather than betray their conscience and their faith."
He said people find freedom when they seek the truth that Christianity offers.
More top news
Mostly dry overnight in the east, strong winds and showery rain affecting Scotland & Northern Ireland
A couple have got married for the second time after the bride forgot their first big day following a car crash.
Sir Bruce Forsyth, Sir Cliff Richard and the Prime Minister have been among those paying tribute to Cilla Black following news of her death.