Question:  While Halloween originated as a Celtic festival known as Samhain.  Pope Gregory the III did this, which lead to what is now known as Halloween.  What was it?

Answer:  The annual festival underwent a Christianized rebranding of sorts in the eighth century, when Pope Gregory III of the Roman Catholic Church deemed Nov. 1 as “All Saints’ Day,” also called “All Hallows’ Day.” The night before the holiday was referred to as “All Hallow’s Eve,” which eventually became known as Halloween. The celebration evolved as it mixed pagan and Christian traditions.