THE GREATEST FRAUD IN HISTORY  (Raymond Bernard) summarizes this theory.

A Startling Revelation of What Really Occurred at the Council of Nicea, Called by the Degenerate Roman Emperor and Homicidal Maniac, Constantine, When Apollonius of Tyana, the True Founder of Essenian Early Christianity, was replaced by a Fictitious Figure Put in His Place, More Pleasing to Constantine, Whereupon He Made the Doctrines of the Persecuted Essenes the Imperial Religion of Rome and Turned his Legions from Putting to Death the Early Christians to Massacring All who Refused to Accept Christianity in its New Romanized Form.