An excellent text about engaging with extremists... (I don't agree with the authors simplification as toddlers) is the book "Subversive Denken, wie man Fundamentalismus diskutiert" (Unfortunately it's only available in German). The author distinguishes between different types of fundamentalists and makes the point that discussions with the convinced fundamentalist is often not possible, because even agreeing on facts is impossible as denying some facts is a proof of faith in the fundamentalist ideology. The discussion is then about convincing listeners instead via different techniques. Despite the title it is not primarily about religious fundamentalism but also political (quite timely at the moment) and the author gives historical examples of the type of techniques employed against fundamentalists.

"Wie man mit Fundamentalisten diskutiert, ohne den Verstand zu verlieren: Anleitung zum subversiven Denken", by Hubert Schleichert