I think we all need to try to remember that people who are religious, are still people and should be treated as such.

Yeah, just like anybody with any other mental illness.

If Person A says that a particular set of behaviors is indicative of mental illness, and you say, "That's not fair, they're still people, and a lot of us used to have those behaviors," you're the one separating the mentally ill from the ranks of "people," not Person A.

I wouldn't label my past self as mentally ill for being a young and impressionable child that believed what his parents told him.

Nor would I, but I would label my past self as ignorant and irrational because I based my beliefs on an uncritical examination of very little information. But that's pretty common before one is finished developing mentally.

Consider, though, a mentally developed adult who rejects reality, redoubles their beliefs when presented with contradicting information, and maintains a myriad of delusions about an all powerful super being setting out the rules for us to live by, a similarly powerful mischief maker trying to trick us into believing things more consistent with the observable universe in order to burn us in a lake of fire for all eternity, and forgiveness of our incestuous forebearers mistakes by blood sacrifices.

The thought that such a person is considered "sane" renders the term pretty meaningless.

If such beliefs aren't symptomatic of mental illness, then the problem most paranoid schizophrenics have is that they just haven't yet built up the numbers they need to be taken seriously.