I think Evil had the right idea.
Evil: God isn't interested in technology. He cares nothing for the microchip or the silicon revolution. Look how he spends his time, forty-three species of parrots! Nipples for men!
Robert: Slugs.
Evil: Slugs! HE created slugs! They can't hear. They can't speak. They can't operate machinery. Are we not in the hands of a lunatic?
In an Open Thread comment beriukay mentioned that he's reading C.S. Lewis' Mere Christianity. I've been reading it too, for interesting reasons.
In my case it so happened that I started discussing faith with a long-time online friend whose spiritual views I didn't yet know, and he turned out to be a Christian with a high regard for the Bible, who also has an interest in science. As our discussion turned to our readings on spirituality, I acknowledged (I think it was me) that I probably spent more time on books that reinforce my point of view than on books that challenge it, perhaps a case of confirmation bias. (I've been exposed to many poor arguments for Christianity, and dismissed them; but possibly that was largely a function of having started out with that bottom line already written and picking arguments I wouldn't have much trouble refuting.)
In the spirit of experiment we agreed to a "trade" - he would read (thoughtfully and with an open mind) a book of my choosing on reasons to doubt faith, and I'd do the same with a book he chose on Christianity.
So the idea here is to pick a book that's the "best argument from the other side" (as in quote 3 here).
I recommended The God Delusion - I'm not sure if that's the best choice given the above intent, but it's what came to mind on the spot.
Would you make a different choice? If so, what?