To him, it's The Truth. Getting you to meetings can only make you understand that! In his head, if he is a believer, that is the only proper outcome. Besides, even if his wife is "spiritually sick" the kids still need to get to the meetings. Just consider things from his POV.
He often do you two talk about this kind of thing? Was this the first time? Was dropping hints and planting seeds not working for you? I would hope that your time on this board would have shown you that the "laying it on the table" approach simply DOESN'T work.
When you do have chats, does he seem to listen or even hear what you say? Does he get defensive? Who usually ends the conversation?
Dont get mad at him when he does stuff like this. Just restate your position respectfully, If necessary. Above all, show him that you're a much better, more loveable person without the org.
Next time the subject comes up, let him speak. Ask him what his position is, how he feels about all of this. Answer his questions clearly and quickly, but above all let him SPEAK. Seek to understand, then to be understood.
Let your parents feel and say as they please for the moment, but do NOT let them influence your hubs in regards to what to do about you.