How can someone discuss “Paradise Lost” without discussing religion?
You stick to the topic, which is Milton, not you or your audience. Telling everyone your own religious viewpoint (and vice-versa) is not discussing Milton. In discussing someone else’s work, you will discuss only their viewpoint and possibly the viewpoint of people who they themselves were responding to or what sort of response people who opposed them presented in opposition to them. Your personal views on religion don’t have anything to do with either literary criticism or literary history. Debating religious beliefs is departing from the topic.