C.S. Lewis writes that he used to think God didn’t exist because the universe was so cruel and unjust. But where did he get the idea that the universe was cruel and unjust? If the natural world is all there is, we have no other standard by which measure it.
And yet we know intuitively that something is wrong with the world. Even if we don’t realize it, we compare this world with the idea of Goodness implanted in us by God. As Timothy Keller says, in order to know that nature is broken, we need to judge it by a “supernatural standard of normalcy.” A supernatural standard implies a supernatural Being who makes His standard known to us. God is the one who gives us our innate sense of right and wrong.