I can only say that it seems pretty normal for rational thinkers to assume non-rational thought to be, shall we say, quirky.
In the nature of things, I see many religions and the doctrines that form them, to be crazy. This is far removed from attaching a similar label to each of the adherents to those belief systems. Still, it is difficult to separate isn't it? When speaking of the ward in which are housed the delusional in an institution, it would be common to name the institution and it's ward, while meaning [but without intending offense] by our words that the residents housed there are intended in the discussion. For what is an institution for the delusional, if there are no delusional attendees.
And if confronting a person of similar delusions, but whom has never [yet] been housed in such institution [or perhaps is not at the moment so housed], it would common to state that it might be the place for them to reside. No?
Religion [as an institution] cannot possess the quality of delusion. Only those who adhere to it could be so considered.
Jeff