H.L. Mencken allowed that his essential problem was probably that there was a void where his spiritual gifts should have resided. "That is to say, I am incapable of religious experience, in any true sense....In that department I am as anesthetic as a church organist, an archbishop or an altar boy." said Mencken in "Sabbath Meditation", pp. 84-85, A Mencken Chrestomathy, New York, Vintage Books Edition, 1982. He went on to say that he disliked any man who was pious and that all that he knew disliked him as well.
Old H.L. seems to have gone straight to the root of the problem: there are many people like Mencken who may or may not enjoy the choir, the ritual, and the fellowship, but who don't feel anything. Such people are regarded as dangerous, misguided, or evil if they talk about this minor lapse, but are perfectly respectable in any society if they keep quiet. Mencken denied he was a militant athiest: precisely so; militant athiests are fanatical joiners and Mencken was neither.
Following Mencken and borrowing some of his terminology, I believe there is a division among men between the Godly and the God Shy. Branching out on my own, I see no reason to deny that it is probably bred in the bone: that is to say, genetic. Perhaps the founding Calvinists glimsed that truth when they talked of the elect and the damned, and argued the differences between foreordination and predestination. The situation is not necessarily too complicated to reduce to the genetic equivalent of, say, the colors of sweet peas. Let us say that there is a Godly gene and that it is partially dominant (big G). Its recessive, the God Shy (or ungodly gene) would then be little g. It is my opinion, unsupported by any systematic research, that all levels of religiosity can be explained by this one hypothetical gene.
Gg These are the backsliders. In sweet pea genetics color them PINK.
gG These are also backsliders. Also PINK.
gg These are the God Shy. In sweet pea genetics color them WHITE.
Militant Athiests? I suspect that they are GG gone wrong. They are true believers and they are joiners, but they have found substitutes for traditional religion. Communism used to be a popular substitute. Green parties are good. Veganism? L. Ron Hubbardites?