God Threshold

William James coined the phrase 'the pain threshold' in Varieties of Religious Experience:

Recent psychology has found great use for the word 'threshold' as a symbolic designation for the point at which one state of mind passes into another. Thus we speak of the threshold of a man's consciousness in general, to indicate the amount of noise, pressure, or other outer stimulus which it takes to arouse his attention at all. One with a high threshold will doze through an amount of racket by which one with a low threshold would be immediately waked. Similarly, when one is sensitive to small differences in any order of sensation we say he has a low 'difference-threshold'- his mind easily steps over it into the consciousness of the differences in question. And just so we might speak of a 'pain-threshold,' a 'fear-threshold,' a 'misery-threshold,' and find it quickly overpassed by the consciousness of some individuals, but lying too high in others to be often reached by their consciousness. The sanguine and healthy-minded live habitually on the sunny side of their misery-line, the depressed and melancholy live beyond it, in darkness and apprehension. There are men who seem to have started in life with a bottle or two of champagne inscribed to their credit; whilst others seem to have been born close to the pain-threshold, which the slightest irritants fatally send them over.

He goes on to ask:

Does it not appear as if one who lived more habitually on one side of the pain-threshold might need a different sort of religion from one who habitually lived on the other?

It sounds eminently plausible; but it seems to me to invite a more thorough follow-through. Is there a 'God threshold' that separates believers from non-believers? Talking of devout Muslims and Christians as 'people with a low God threshold' might be less ostensibly offensive than calling them gullible; plus it addresses the specifics of belief, since an individual who is (as an atheist might see it) 'gullible' when it comes to God might very well be far from gullible in other areas of his or her life.