It was as one might expect - shocking and upsetting to everyone, but for me, it was also hilarious. I told my parents that I'm an atheist, and to confirm, they asked if I don't believe in Jehovah, Jesus, or Satan, to which I responded affirmatively. Then they asked "so all of them are fairy tales to you?" I answered yes. They then threw their hands in the air, and said "Satan has taken you", and then they were overcome by a confused frustration, saying "oh but Satan doesn't exist to you". I could see the cognitive dissonance causing a few sparks in their heads.
After they let the day's events simmer overnight, they made the decision to kick me out.