That was my first thought as well, Ken.
I guess I'd try to diplomatically discuss it with him, e.g. "I respect your religious beliefs and your right to voice them to whomever you please. But as your friend, I feel I ought to let you know that when you do so so often, or so forcefully, it makes me and some of your customers uncomfortable. Do you think you could dial it back a little? I'd like to keep working with you. You're a hard worker, your prices are good, and you're reliable. Whaddaya say?"
Hopefully he will be able to have a light bulb moment and realize that not everyone thinks the same way he does. It may be as simple as that.
However, there is the possibility that he'll double down on the sermonizing, with or without getting annoyed/agitated.
Sounds like you've anticipated how a talk would go. I'm not sure if I'd give it a shot or just sit on it.
Good luck!
