The Christian origin of the holiday is that it falls on the days before the feast of All Hallows, which was set in the eighth century to attempt to stamp out pagan celebrations. Christians would honour saints and pray for souls who have not yet reached heaven.
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.
Harley Quinn is so last year (even though she is getting her own Suicide Squad spinoff), and this years Halloween calls for something new. If you want a Halloween costume that no one will expect but everyone will appreciate, look no further than these 30 original (and inexpensive!) costume ideas.