But references that God can be seen are prevalent (Gen 12:7, 17:1, 18:1, 26:2, 26:4, 32:30, 35:1, 35:7, 35:9, 48:3, Ex 3:16, 4:5, 6:3, 24:9-11, 33:11, 33:23, Num 14:14, Dt 5:4, 34:10, Jg 13:22, 1Kg 22:19, Job 42:5, Ps 63:2, Is 6:1, 6:5, Ezek 20:35, Am 7:7, 9:1, and Hab 3:3-5).
But that's irrelevant. We don't see gravity; we don't see radio waves. God is not "natural" so naturally He cannot be seen or detected naturally. Our concepts of justice, mercy and love do not stem from physics or the stone-cold universe we live in. Besides, Christianity can visualize God through the icon of Jesus. It is the only religion that has a personal connection with God on a human level, so his claim that all religions worship something unknown is only partially true.
Theology is a little more complicated than basic Philosophy 101 this individual spouts. We will never know the essence of God (how can a tool know its maker?), but we recognize God through His energies (manifestations). Traviskicks simply doesn't even measure up to the subject.
As for atheists and agnostics, who cares! If they think this world just happened to come into existence by itself -- and I mean not just the tiny little earth but all of the Universe -- let them. It's not their intellect that stops them but their pride and a western love-affair with humanity that has been elevated to deity.
You really don't put much effort into understanding the Bible.
Try to read it hermeneutically, meaning in context. Also, get a Bible that does not compress 60,000+ foreign words into a mere 16,000 English ones (in the case of the New Testament).
You will never understand the truth in the Bible until you put in decent effort. I have found many things that seem contradictory at first later become entirely synergistic. A ridiculously simple, juvenile example is "peace through war." The immature says, "of course you cannot have peace with war!"
As for atheists and agnostics, who cares!
God does.