Slughorn?

My god... it's Jack L. Chalker. The author of that sweet Demons at Rainbow Bridge" book.
He looks like Proffesor Slughorn. (Not quite my vision.)
I feel like while googling this book, I got a lot of religious allegory.
I'm going to return to my search...

http://www.fantasticfiction.co.uk/c/jack-l-chalker/