It seems obvious in the Christian model why God would give us reason. It is to decipher right from wrong, in the way that he instructs us to decipher it. If we ignore the instruction in the bible, though, we can use reason to come to many different conclusions, sometimes those that oppose God's wishes. Why would God gives us eyes, letting us see the apparent godlessness of this earth, and endow us with reason, to further let us stray from his true path? Is he a great deceiver?