Just because mankind doesn't have the answer, or thinks the answer is unknowable, doesn't mean that there is no answer or that the answer is unknowable.
We come back to the age old question, if G*d is omnipotent can he make a boulder big enough that even he can't move it?
If G*d is omniscient there is nothing he doesn't know. Just because mankind doesn't know doesn't mean G*d doesn't know.
What you don't understand is that both states in total, don't exist. It isn't a matter of knowing, it doesn't exist and that is why an omniscient God can't know. Ergo an omniscient God doesn't exist :)