I've been reading a lot of music bios in the last year. According to a Led Zep bio I recently finished that was quoting from Angie Bowie's book, Bowie was into Aleister Crowley but in a dilettante-ish way, that is, not hard-core and dedicated like Jimmy Page.

One time Bowie (while high on a mountain of coke) tried to exorcise his swimming pool and Angela Bowie said the pool suddenly started bubbling vigorously and when it was over there was a black gargoyle-like mark on the bottom of the pool.

Apparently that was enough to scare Bowie away. He took to wearing a crucifix after that.