To say the least, we human beings have a powerful intuition about good and evil, right and wrong. We Christians argue that the only way that “the good” has any meaning is if it’s rooted in a transcendent reality, namely God. This is a powerful argument for God’s existence.
It doesn’t prove anything, of course. We could as a species be cursed with a powerful sense of morality, which, although remarkably similar from one person to another, is, like all products of evolution, merely an accident. Morality is therefore arbitrary and subjective.
The atheist, in other words, feels in his bones as strongly as any believer that rape is wrong, and will take action to prevent it as often as any believer. But in the cool light of reason, he must tell himself that his feelings are unjustified and meaningless.
Fortunately, even the most strident atheist fails to live down to his principles.
Alister McGrath, in his book Mere Apologetics, gets it exactly right when he writes:
At a popular level, atheist apologists react with anger to such problems of their ideas, suggesting that it amounts to suggesting that they are immoral. It doesn’t. It’s not denying that atheists have moral values. It’s asking how these values are justified… Atheist philosopher Iris Murdoch argued that a transcendent notion of goodness was essential if defensible human notions of “right” and “justice” were to be maintained. If she’s right, our longing for justice is itself a deep clue to the meaning of things.[1]
1. Alister McGrath, Mere Apologetics (Grand Rapids, MI: Baker, 2012), 108.