It is widely understood by mental health professionals that religious delusion is a common symptom experienced by many people suffering from a variety of mental illnesses. This observation, however, requires a certain convention be adopted for the purpose of defining just what religious delusion is.
Broadly speaking, a delusion is a persistent false belief in something despite contravening evidence or reason. Under this working definition, is it fair to describe those who have religious faith as delusional? For the most part, it would seem not. Practically speaking, it seems whether or not a belief rises to the level of delusion can be gauged by its relationship to behavioral anomalies. If someone says God commanded him to commit murder, it would be understood that religious delusion is at work, not because God's existence can be disproved, but rather because the belief in God's existence resulted in antisocial behavior. Delusion is not necessarily dependent upon the false premise of any particular belief, but rather on its propensity to negatively impact behavior.
But what about other more subtle manifestations of questionable belief? It may not be considered delusional for someone who believes in God to tell those who do not they will go to hell, but if this belief is so deep-seated it interferes with relating to people in general, the label of "delusional" could surely apply. Given that achieving and maintaining stable, loving relationships is one measure of positive mental health, the absence of such relationships in the life of someone possessed of extreme religious faith suggests a delusional aspect to such beliefs.
Another symptom commonly associated with religious delusion is obsession. The religiously obsessed see all things through the narrow prism of their own religious faith. Such thinking is unhealthful because it is dismissive of those who employ any of life's other prisms of discernment, thus complicating the building of relationships based upon more universal concepts or even trust. In addition, the religiously obsessed often endure profound stress at the thought - or experience - of having their religious beliefs questioned.
Among other reasons, one could be said to be suffering from religious delusion if:
- the beliefs in question impede one's ability to cultivate and maintain meaningful relationships, or;
- they are the direct motivation for overt acts of antisocial behavior.
Finally, it is important to remember that those experiencing delusions of any kind are, by definition, grappling with mental illness, and as such are deserving of compassion and understanding, not ridicule or contempt.