The False Prophet is depicted as an agent of "The Beast" and predicted to be cast within The Lake of Fire along with its master.
According to Travis Marshall, Dexter Morgan was The False Prophet that tried to lead him "astray" from the Path of God. At first, Dexter believed that Professor James Gellar was The Doomsday Killer. In reality, Gellar was dead from the start and Travis acted alone while believing in an illusion of Professor Gellar.
The term "False Prophet" was used by Professor Gellar which, in turn, led to Travis accepting the concept. Travis began to express his darkness in the form of Gellar. After Travis realized the truth that he had killed Gellar, he stopped seeing Gellar's illusion. He then named Dexter as The False Prophet.
The final major tableau was The Lake of Fire, and Travis intended to kill Dexter by casting him into burning waters. Dexter, however, managed to narrowly escape from his predicament. ("Talk to the Hand")