For believers of God and Christ, it seems that it should be obvious that Babylon the great of Revelation should be all religions and spiritual practices associated with the one true enemy of Christ...the devil, satan, the snake etc.
Essentially any group or individual practicing and promoting witchcraft, sorcery, devil worshipping etc. All things practiced in ancient Babylon (the nation presumably used as the model for the one in Revelation).
Or is this too simple of an explanation?