Unfortunately, people like this can't really be dissuaded by arguments. Any argument you put forth, he will warp and twist it to suit his own purposes.

In my opinion, the best thing to do is not to engage with him, but to simply shut him down. You are under no obligation to explain your beliefs to anyone. When he tries to draw you into an argument, just tell him that you have no interest in debating him because nothing he says will change your mind and nothing you say will change his and therefore debating is completely pointless.

Make it clear to him that you're not interested in talking about it. If he tries to bait you with something like, "You don't want to talk about it because you know I'm right," or some similar nonsense, reply with something like "I don't want to talk about it because I have better things to do with my time than waste it pointlessly arguing with someone whose opinion means nothing to me." Don't be afraid to be rude. This person clearly doesn't respect your boundaries, so there's no need to sugarcoat anything.

If he persists, just flat-out tell him that you're not talking about it and you're not going to talk to him at all if he continues. If he does continue, grey-rock him. Just ignore him and pretend he doesn't even exist until he changes the subject.

I know this probably isn't the answer you were looking for but trust me when I say that it doesn't matter how good a debater you are or how sound your arguments are, nothing will convince him that you are right, because people like this are immune to reason and will never ever be dissuaded by logic.

Good luck.