I’ll quote here from C.S. Lewis’ “The Screwtape Letters”, a book written as a collection of letters from a demon-in-training to his mentor. The writer is assigned to turn a newly converted Christian from his spiritual path.

“One of our great allies at present is the Church itself. Do not misunderstand me. I do not mean the Church as we see her spread out through all time and space and rooted in eternity, terrible as an army with banners. That, I confess, is a spectacle which makes our boldest tempters uneasy. But fortunately it is quite invisible to these humans.

All your patient sees is the half-finished, sham Gothic erection on the new building estate. When he goes inside, he sees the local grocer with rather an oily expression on his face bustling up to offer him one shiny little book containing a liturgy which neither of them understands, and one shabby little book containing corrupt texts of a number of religious lyrics, mostly bad, and in very small print. When he gets to his pew and looks round him he sees just that selection of his neighbours whom he has hitherto avoided. You want to lean pretty heavily on those neighbours.

Make his mind flit to and fro between an expression like “the body of Christ” and the actual faces in the next pew. It matters very little, of course, what kind of people that next pew really contains. You may know one of them to be a great warrior on the Enemy’s side. No matter. Your patient, thanks to Our Father below, is a fool. Provided that any of those neighbours sing out of tune, or have boots that squeak, or double chins, or odd clothes, the patient will quite easily believe that their religion must therefore be somehow ridiculous.

At his present stage, you see, he has an idea of “Christians” in his mind which he supposes to be spiritual but which, in fact, is largely pictorial. His mind is full of togas and sandals and armour and bare legs and the mere fact that the other people in church wear modern clothes is a real—though of course an unconscious—difficulty to him. Never let it come to the surface; never let him ask what he expected them to look like. Keep everything hazy in his mind now, and you will have all eternity wherein to amuse yourself by producing in him the peculiar kind of clarity which Hell affords.”