Atheist: Did I overreact or did I do the right thing?? (long read)?

From your description, it does sound like he was trying to put you on the spot. It sounds like you handled the situation up until the point where you walked out of the church and then punished him afterwards. I would have firmly told him that I would not put the money in the plate myself, and if he insists that I must then I'm keeping it. I don't see how lashing out at him afterwards helped anything. A calm discussion where you express how his actions made you feel would have been a wiser approach.