I like the quote; its very true; but the religious side doesn't hold to it. Scientists are very happy to say that we certainly DO NOT know everything, or even a lot about the stuff we DO know. The point is that religious authorities CLAIM to KNOW things where they really can't say. Such as... "there is a hell" and "it is a real place for sinners" as well as "God exists". These are certainly things that they can't prove, yet they claim to know these things as if they were facts. We're actually glad to be able to ADMIT that we don't know; that means we have more stuff to work on so that we will!
This is what most Militant AGNOSTICS will say to any religious leader: I DON'T KNOW, AND YOU DAMN WELL DON'T KNOW EITHER!