The Reformers, specifically Luther, put Revelation at the back of the Bible becuase he felt it was "less than inspired". In fact, the last 5 books of the Bible, from Hebrews to Revelation, are specifically at the back of the Bible because Lutherans wanted to drop them from the Bible just like they did the Apocrypha. Hebrews has an unknown author and as such lacks any kind of authority on which to base it's pseudo-Hebrac paganized version of GOD.