That's because the proposition was "everybody worships something, including atheists, even though they might not know it" not "I'm a Christian prove me wrong".

You're confusing it with a Crowder sketch maybe.

Kid is like 'but I said you said Christians worship Mary above everything else and now you're saying she's not worshipped as much as the trinity haha gotcha!'. This kid was raving like a lunatic and in a better day Peterson would have just reached over and smacked him upside the head.