the most productive disagreements are between people who share a common foundation. the actual most likely result of sending a long effortpost in reply to someone like this is that they'll cherrypick pieces of what you said and try to paint you in the worst possible light - assuming they don't ignore everything you said and just ramble at length on whatever they feel like talking about. moreover, no one is owed your time. the fact that someone wants a debate doesn't mean you have to give it to them. this is all just basic social hygiene.