On social media an atheist was debating a Christian, making the argument that God is not necessary for morality to exist. He laid out his case as follows. In World A God does exist, and in World B God does not exist. The atheist asked the Christian, in World A if someone throws a baby off a building is it wrong? The Christian answered yes. The atheist then asked the Christian, in World B if someone throws a baby off a building is it wrong? The Christian responded yes again. The atheist then concluded that he had proven morality does exist without God.
Did the atheist really prove his case? No, not at all. The Christian should have answered the question about World B as no. Because in a world where God does not exist it is not wrong to throw a baby off a building. Without God there is no basis for the concepts of right and wrong. By what standard could the atheist even determine that throwing a baby off a building is wrong? Without God there is no ultimate and final authority. You would be left with nothing more than one opinion versus another opinion.
If humans just somehow happened, if humans are just chemicals reacting, and if humans just cease to exist when they die, then nothing really matters anyway because humans would have no value. The only consistent response for an atheist to anything that happens, including throwing a baby off a building, is so what?
When an atheist thinks throwing a baby off a building is wrong he is actually borrowing from the Christian worldview. The atheist cannot escape the fact that he is made in the image of God and must live in God's world. He cannot consistently live out his own worldview. A baby matters and has value because he was created by God in his image. Throwing a baby off a building is wrong because it is a violation of God's law and character.