answered. The reason we know that God exists is because He has told us so, and has revealed Himself to us. It would be no help to us at all in our human predicament if God were silent, but happily this is not the case. God not only exists, but also He has communicated that fact to us. He has told us all about who He is, what He is like, and what His plan is for planet earth. He has revealed these things to mankind through the Bible. The Bible has demonstrated itself to be more than a mere book; it is the