Hey! I've got a pastor father too, but thankfully my atheism doesn't seem to be a big deal for him. (It helps that I don't live nearby.)

I think the "conflicting belief system" is, as I understand it, the right model. There's a Christian worldview, which has some basic assumptions (God exists, the Bible is a useful source for learning about God, etc.), and there's a reductionist worldview, which has some basic assumptions (everything can be reduced to smaller parts, experiments are a useful source for learning about reality, etc.), and the picture you can build out of the reductionist worldview matches the world better than the picture you can build out of the Christian worldview. (There are, of course, other possible worldviews.)

I would not put much hope into being able to convince the people at this event that they should be atheists; I wouldn't even hope to convince them that you should be an atheist. And so the question becomes what your goals are.

If you're concerned about recanting your atheism and meaning it, the main thing I can think of that might be helpful is the how to change your mind sequence. You can keep that model in mind and compare the experience you're undergoing to it- it's unlikely that they'll be using rational means of persuasion, and you can point out the difference.

Are there people I can be put in touch with, or online meetups where I can talk to people and arm myself? Should I start a discussion post, or what? I'm unfamiliar with the site structure here, so I could use some help.

Starting a post in discussion is an alright idea; it'll work well if you mention specific arguments that you want to have responses to.