Gates to Paradise (1968)

Gates to Paradise is a 1968 film by Polish director Andrzej Wajda. The film is set in medieval France and is based on a story by Polish writer Jerzy Andrzejewski (1960) that seeks to expose the motives behind youthful religious zeal. It was entered into the 18th Berlin International Film Festival.
In 1212, a Children's Crusade is launched after Jakob (John Fordyce) claims to have had a vision in which it is said that the innocence of children would be able to liberate Jerusalem. A monk (Lionel Stander), returning from Jerusalem, joins the crusade and hears the children's confessions, gradually realizing that most of them are taking part not for religious, but for more worldly reasons, like rejected love.