Small Gods is indeed a great choice. I never thought of it as a “book for atheists” and it’s quite unlikely to turn someone religious into a non-believer - but it’s clever, funny and one of my personal favorite Terry Patches books. So, worst case scenario: you’ve read a highly entertaining book.

“The Bible” is the book that ultimately turned me into a convinced atheist. If you actually read it, without having it filtered and read to you by religious people with agendas, it’s hard to continue believing in any of its insane ramblings. But it’s a really tough, slow and often immoral and revolting read. Mostly, it’s just really stupid.

“The Gospel of the Flying Spaghetti Monster” is the opposite. It’s a funny, light and often silly read. It’s not exactly deep, but neither are the books it’s parodizing. As a satire of other religious text it works reasonably well in putting the finger in the wound.

“The Portable Atheist: Essential Readings for the Nonbeliever” is just that: a collection of texts and letters on the subject by some brilliant minds: Bertrand Russell, Albert Einstein, Mark Twain, Lucrecius, Charles Darwin, Richard Dawkins and many more … collected and edited by Christopher Hitchens. As an anthology it allows you to dip your toes in and read the texts you are interested in. Maybe my first choice as serious “atheism for beginners” literature.