The Lord is invisible, but he has not hidden himself. The Lord shows himself by His self revelation. The Lord leaves his signature in this creation, and the Lord gives us his word. While we as humans can never know God exhaustively we can still know God, and more importantly God knows us. So, if the Lord gives us his word how do we know that his word is certain? How do we know that the Lord can use the gifts of the man without contaminating his word?