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
A remarkably mild night with misty low cloud on the hills of Scotland, Wales and north-west England and further rain in places.
The former head of the Diplomatic Service breaks down the hidden meanings behind Theresa May's letter to Donald Tusk
The storms that struck Texas and Oklahoma late on Tuesday brought tornadoes, tennis ball-sized hail and powerful winds.