I'm not trying to guess why you would say that (and by that, I mean the fact that you would avoid writing because it's trying to preach to you), and I do want to say that Lewis is, overall, very close to proselytizing in his writings (generally it's pretty explicitly stated that's what he wants to do). But.

Avoiding something because it disagrees with your worldview, or because it is 'too close to [insert literally anything here]' is not a great way to expand your understanding of the world. Being exposed to things you disagree with is step 1 in understanding how or why they exist, with few exceptions (CP, explicit hate speech, most calls to violence, those sorts of things).

Read the screwtape letters. Yes, they're intended to make you consider your immortal soul and embrace Christianity. But also yes, it's an amazing piece of literature.