Many people have serious doubts about the objective existence of morality. In fact, more people probably have doubts about morality’s being real than have doubts about God’s being real. The sentiment is that moral values or moral judgments do not have a real status the way facts like 2 + 2 = 4, or “the speed of light is 186,000 per second,” or “the Earth orbits the Sun.” These sorts of claims we can prove. We can investigate empirically and see that they are true. We can reach widespread agreement about them. But moral values, whatever they are, cannot be assessed this way. People rarely agree, there are no empirical tests for what is right or wrong, and they seem unavoidably subjective. It seems more likely that there really isn’t any such thing as real moral truths. There are only different cultures, different eras in history, and different people who have varied views about what is right and wrong. But right and wrong aren’t anything above and beyond those social constructs.
I don’t think this argument is correct, but that’s not my topic here. What are the implications of having this anti-realist view about morality for the existence of God? The answer is that if you don’t think that morality is real, then you should conclude that there is no God.
Premise 1. If right/wrong, good/evil are nothing but social, human constructs, then nothing is really good (good beyond those social, human constructs.)
Premise 2. But if nothing is really good, then no being can be all powerful, all knowing, and really all good.
Premise 3. If nothing can be all powerful, all knowing, and really all good, then nothing can be God, or God doesn’t exist.
Conclusion: 4. So if right/wrong, good/evil are nothing but social, human constructs, then God doesn’t exist.
Premise 3 might be unclear. I’m stipulating, with lots of agreement from others, that in order to be God, to be worthy of the title, a being needs to be all powerful, all knowing, and all good. That’s a widespread view. It’s the foundation of the entire western Judeo-Christian-Islamic traditions. But we don’t have to define God as only an omni being. If someone chooses, they could allow that some lesser being is going to be called “God.” If we’re going to do that, then we all need to be clear about the terms and what’s intended by them. One reason to not demote God to some lesser being is that a lesser being, while impressive perhaps, wouldn’t be worthy of worship, and wouldn’t be nearly as significant personally, philosophically, and so on. Another question would be, what grounds do we have for thinking that some lesser being than God exists? The argument above shouldn’t be construed as granting permission to believe in a god as long as it isn’t an all good one. All beliefs need some kind of justification to be reasonable. So that lesser god belief would need substantial support too.
Typically, believers will reject this argument. Many of them will believe that both God and moral values exist. This argument doesn’t preclude that sort of response—although that response has lots of other problems as other posts have discussed. There’s nothing in this argument that prevents us from concluding that moral values are real, but God is not—the moral realist atheist. And there’s nothing here to prevent us from concluding that neither God nor morality are real—the moral relativist atheist. But moral relativism and theism are incompatible. The result here is that if you believe that there really is no such thing as objective moral values, then there is no God.