/lit/ - Literature

as someone who pretty much only reads nonfiction and historical fiction, I'm really enjoying myself in this thread so far. This is terrific.

How do I convince someone who doesn't think good or evil or God exists and is a Nihilist that at the very least they should be critical of their own beliefs? On the idea of good I've been able to make them contradict themselves, but they still deny everything. (Problem here not being that they don't believe in anything, but rather that they can't look past their own bias and at least consider an alternative.)