Question: "Of all the things in the whole wide world that there is to know, what percentage of it do you know?"
An honest person couldn't really give a very high percentage (I give myself less than 0.05%! ;-) ). But let's pretend he says 30%.
The question to ask then is, "What if God is in that 70% that you don't know?"
It occured to me the other day that to suppose there is no God just because one cannot see Him is a very proud, self-filled, narrow-minded way to think. "I can't see it, so it must not be there." As it says in John, we have never seen the wind-- we see only the effects of it. We cannot see God with human eyes, yet we know He is, because we see His handiwork, His providence, and His self-revelation in His Word.
Jesus says, "Blessed are they who have not seen [Me], and yet have believed" (John 20: 30). "Now faith is the substance of things hoped for, the evidence of things not seen" (Hebrews 11:1). God honors the simple faith that believes Him for Whom He has said He is. O for the day when faith becomes sight, and all those who rejected a God that they could not see will at least be convinced "that He is, and that He is a rewarder of them that diligently seek Him" (Hebrews 11:6).