I posted this elsewhere but it's the same idea. They seem to follow more or less the basic plan for any type of apologetic, which is as follows (with a few more points I've added):
You can't argue by contradiction in this way and expect to make progress because *ahem* the supernatural doesn't actually exist, so the book can just be redefined because the limit of interpretation isn't based on reality, it's based on your mental gymnastics. But a book can be totally internally consistent and totally false, so I recommend challenging the latter, not the former.