Why doesn't God expect an unbeliever to be a good person?
Because the carnal, old Adamic mind is enmity against God and is not subject to His law. The unbeliever is in rebellion, refuses to admit sin or spiritual lack, and is therefore an enemy. God sees his nature is anything but good, so He does not expect him to keep His law.
Les explains that the carnal or old Adamic mind is enmity against God, and it is not subject to the law of God. The unsaved person is in a state of rebellion: he will not do what God says, will not admit that he is a sinner, and will not admit a spiritual lack. That rebellion makes him an enemy. Because God sees down into that nature and knows it is anything but good, He does not expect the unbeliever to keep His law or to be a good person. Les also remarks that it is amazing man is as civilized as he is.