For what it’s worth, (as a fellow college student parent) at this point, I would just let him go. He’ll likely read any of these choices and while doing so, will make notes of the things he disagrees with and you’ll be able to talk about it over Turkey in November.
My daughter read Hitchens in Dawkins her senior yr of HS and had sticky notes all over the place with notes refuting their claims.
Alternatively, If you must, then once you find out which book he’s reading, pick up a copy of yourself, read it and then engage in discussion.
You could also get him some books for Christmas that are more in line with supporting Christianity to counterbalance this assignment