There's this devotee--let's call her K--who believes that her tradition's sacred text is the word of God. Mind you she's not a Christian. K has unwavering faith (i.e., belief) that it is her god who's for real and that every word in what she considers the holy text comes from this deity of hers. Asked what she thinks of the gods of other religions, she coughs out a snicker and says simply, "As real as Cthulhu and Voltes V."
My question is, Why is it that not every theist, every human who yearns to be God's toadie has faith in K's deity and holy book? Why is it that bible toters and Vatican geezers don't have faith in this god, the supernatural entity that's purportedly the only real and true being up there? And more importantly, why the heck don't you believe? Sigh. Ye men and women of little faith!
Ask devout Hindus, Parsis, Muslims, Jews, ... whether their deity is the real McCoy and whether their scriptures are the word of their deity/deities. Bring me one who says no.
We can have faith in a billion and one things. And yet believing, believing ardently, believing till our brains explode in ecstasy (no, not the pill) isn't going to make what we believe in true and real if it just ain't so. Dozens if not hundreds predicted the world would end before today. And yet all these forecasts are now history! However much gullibles may have believed in them, they were absolutely wrong. Beliefs are, literally, only in the mind. Thus, "utterly stupid" is what describes the act of going about raving and coaxing others to have faith. That clarion call "Have faith"--to believe fervently despite the lack of evidence or even because there is no evidence--is today's PC phrase for "Please, please delude yourself."
The next time an ecstatic religionist sidles up to you like some MLM (multi level marketing) salesman, keep in mind that that person, at least vis-a-vis the nonexistent product he's persuading you to invest in, is totally bonkers and is psychotic and has bought into a tale he (desperately) wishes to be true.*
When accosted by such a crazy fool subject him to this acid test: Ask him to show you the product. Demand that he produce this deity he's so gaga over. No demo, no go. If he insists he can't and argues that that's why you need to have faith, then tell him all about the honest-to-goodness fire-breathing dragon in your garage which, just by coincidence, you can't make visible either. Which means that he must have faith that this hydrogen-expelling creature is in fact in the driver's seat of your invisible 500-hp Ferrari. And for good measure tell him about how that innocent, beat-up 1.3-liter Toyota parked in there regularly transubstantiates into a Lamborghini whenever it hits the streets. "Faith, my boy. Just have faith all this is true."
* "Normal" people can have transient psychotic episodes and can compartmentalize their minds, chronically, such that one or two or more beliefs or ways of thinking are totally irrational and incongruous with the rest of what's in his head. Thus, an engineer may be an expert in constructing bridges and a top-notch professor of civil engineering, but can harbor such wacky, ludicrous beliefs as aliens abducting humans just to have sex with them. (See Michael Shermer's Why People Believe Weird Things.)