How did Halloween get its name?

Halloween was originally called All Hallows' Eve which means the evening before All Saints' Day. "Hallow" is an Old English word for "saint". This was shortened to Hallowe'en and finally to Halloween. Satanists have adopted Hallowe'en as one of their three main seasonal days of celebration. The others are Walpurgus Nacht on MAY-1 and the Satanist's birthday. All-Saints-Day and All-Hallows-Eve were never celebrated together. it has always been the day after.
Halloween's name is a shortening of All Hallows Eve, the day on which some believe all the bad spirits come out.