I'd agree with that. Claiming to know the unknowable is arrogance. But that sword cuts both ways. Someone claiming to "know God's Will" is either deluded or a fraud. But so is someone claiming to know "for a fact" that God doesn't exist and anyone that thinks he does is a "moron"
Who here said that they "know for a fact that god doesn't exist?  Also, the rail is against religion and all the moronic beliefs that go along with it.  Being agnostic about the possibility of a super intelligence is one thing, but to believe such nonsense like the earth was created in 7 days, Humanity was fashioned from clay (woman from Man's rib), virgin birth, and that some carpenter will save your eternal soul from an evil spirt that inhabits a magical realm is moronic.  Honestly, if you take away the emotional attachment from the Christian religion and look at it rationally, one can easily see how silly it is.  I can't imagine anyone but a complete idiot actually believing this nonsense.  If you live your life based on such garbage, then you must be a moron.
As for Einstein--I could see one arguing the case that he was slightly agnostic, but only the the extent that because the possibility has not been proven false, it is still theortically possible.  Many people will try to take a minor sampling of his quotes and use them to build the case that he actually believed in some higher power.  That simply isn't true.  The lack of total denial does not equal belief.