To insist that all religions are right, that all the roads are going to the same place, is actually silly… We’d have to be intellectually intolerant.
Hitler, for example, believed he was on a divine mission… Nazism really had very religious roots, and yet the world by consensus has decided that it’s not valid. As soon as you send judgment on that particular religion, then you’re already denying your original principle.
Theological tolerance of religions is absolutely impossible for anybody. When you say to me, “You mustn’t try to convert people to your religion, as if your religion is superior,” what you’re really saying is, “I want you to abandon your inferior view of religious truth and take my superior view”… [saying] that your view of religious truth— that all religion is relative— is superior to my religious truth— that some religious truths are absolute. And so you’re doing the very thing you say I shouldn’t do… What you’re immediately saying is “Your road doesn’t go the same place. You’re actually saying, “My view of religion is superior to your view of religion.”
So to say all religions are relative is a religion… To say you can’t judge between religions is to judge between religions. To say you can’t determine right and wrong beliefs is a determination of right and wrong beliefs… To insist that no religious truth is superior (and by doing that insist that your religious truth is superior) is completely inconsistent.
-Tim Keller from “Authentic Christianity”