> At what point do we consider any religious beliefs that have deleterious effects on oneself to be mental illness?
Religion is basically always a socially acceptable mental illness that we not only tolerated but encouraged because it has been a part of civilization since before we formed the basic premises for what constitutes a civilization.
For any society to exist, we have to pick something to believe in. And anything we pick, will have contrary evidence or not make sense at least some of the time.
That doesn’t make it an illness, unless it produces massively negative outcomes.
Religion is basically always a socially acceptable mental illness that we not only tolerated but encouraged because it has been a part of civilization since before we formed the basic premises for what constitutes a civilization.