Reddit reviews The Little Book of Big Questions

First, keep taking him to church if he wants to go. I'd give him a timeline of when you'll stop going with him though else he'll hold out hope of reconverting you and that isn't fair to him. However, start taking him to science lectures and free thinker meetings or skeptics meetings or whatever you have in your area. Talk to him about how difficult it was for you and that you understand he's confused and that's it's ok if he still believes which I know you've done but keep doing it.

The Little Book of Big Questions would probably also help as the idea of god is just one of many questions with many possible answers. It will get him thinking logically.