So the Christians say that God exists and speaks through the Bible and that the Bible is really the only "trusted" source of what God is capable of doing. It explains how God created the universe and how God is all knowing and all powerful. But, what if God was lying? What if God did not create the universe or He has not all knowing or all powerful. I mean, the only reason we think that is because the Bible says so, and God wrote the Bible, so if God lied, how would we know? Some may say that God speaks directly to them, but again, what if God is lying? How would you know? The God that we know may be just a third rate celestial being that sneaks around behind the real Creator's back just to mess with humans while the real Creator totally ignores everything going on in this universe.
