From C.S. Lewis, Mere Christianity, pp. 29-31
“We have two bits of evidence about the Somebody. One is the universe He has made….The other bit of evidence is that Moral Law which He has put into our minds. And this is a better bit of evidence than the other, because it is inside information. You find out more about God from the Moral Law than from the universe in general just as you find out more about a man by listening to his conversation than by looking at a house he has built.
Now, from this second bit of evidence we conclude that the Being behind the universe is intensely interested in right conduct–in fair play, unselfishness, courage, good faith, honesty and truthfulness. In that sense we should agree with the account given by Christianity and some other religions, that God is ‘good’. But do not let us go too fast here. The Moral Law does not give us any grounds for thinking that God is ‘good’ in the sense of being indulgent, or soft, or sympathetic. There is nothing indulgent about the Moral Law. It is as hard as nails. It tells you to do the straight thing and it does not seem to care how painful, or dangerous, or difficult it is to do. If God is like the Moral Law, then He is not soft….you know at bottom that unless the power behind the world really and unalterably detests [human greed and trickery and exploitation], then He cannot be good. On the other hand, we know that if there does exist and absolute goodness it must hate most of what we do….God is the only comfort, He is also the supreme terror: the thing we most need and the thing we most want to hide from.”