I don’t believe that to be true. Con-men know that they are deceiving people. Con-men do not believe their lie. These people may have convinced themselves of their lie. It may be self-delusion, but that doesn’t make them believe any less in their statements.
Human beings are not rational. While it may seem insane that someone can convince themselves of something they know to not be true. This is self-deception. This is a well-documented phenomenon that occurs with human beings. People can and do convince themselves that they have done things which we know to be untrue.
Fundamentalist Christians “hear the voice of God”, they “witness miracles” that never occurred. They can twist events to match their beliefs. This may have started as a lie or as a self-deception, but these “ex-Satanists” have gone on to SWEAR BEFORE A COURT OF LAW that they can point you to the hidden bodies that they buried. These people are not just lying, they truly believe their lies. This places them in a category with a great deal of moral ambiguity.