I stopped trying, years ago. I figured they had delusional, perhaps even the beginnings of the Strong Delusion, and reprobate minds.
Any more, I just nod and walk away, for the most part.
That’s probably the best approach. There are still people, after eight years of supposedly observing Obama in action, who believe he is truthful/doesn’t lie. Nobody is ever going to get anywhere with people as—to use your word—delusional as that.