The origin of the festival is disputed, and there are both pagan and Christian practices that have evolved into what Halloween is like today.
More than a thousand years ago the Christian church named November 1 All Saints Day (also called All Hallows.) This was a special holy day to honor the saints and other people who died for their religion. The night before All Hallows was called Hallows Eve. Later the name was changed to Halloween.
Nicholas Rogers, a historian at York University says that when people prayed for the dead at Hallow Mass, they dressed up. When praying for fertile marriages, the boy choristers in the churches dressed up as virgins. So there was a certain degree of cross dressing in the actual ceremony of All Hallows Eve