Heretics and nutcases are not bound by truth. Lies abound among them. It just is the way heretics are.
Some simply cannot tell the truth even when there is nothing to be gained by lying or when the truth might actually be beneficial. There are certainly some anti-Catholics who are sociopathic pathological liars.
A sociopath is defined as someone who lies incessantly to get their way and does so with little concern for others. A sociopath is often goal-oriented (i.e., lying is focused - it is done to get one's way). Sociopaths have little regard or respect for the rights and feelings of others.
Pseudologia fantastica is one of several terms applied by psychiatrists to the behavior of habitual or pathological lying. The defining characteristics of pseudologia fantastica are that, first, the stories told are not entirely improbable and often have some element of truth. They are not a manifestation of delusion or some wider form of psychosis: upon confrontation, the teller can admit them to be untrue, even if unwillingly. Second, the fabricative tendency is long lasting; it is not provoked by the immediate situation or social pressure as much as it originates with the person's innate urge to act in accordance. Third, a definitely internal, not an external, motive for the behavior can be clinically discerned e.g. a sense of inadequacy might cause a person to lie repeatedly, without the lying being a pathological symptom.