I believe I have written on this in the past, but it’s worth mentioning again. Consider what I am calling the “Best Explanation” Moral Argument for God’s existence.
1. Probably, if God does not exist, then objective moral values and duties do not exist.
2. Probably, objective moral values and duties do exist.
3. Therefore, probably, God exists.
The conclusion is an entailment of the two premises. That is, if the premises are true, then the conclusion must be true as well. More precisely, it’s not possible that both of the premises are true and the conclusion false. So, in order to deny the conclusion, one must deny at least one of the premises as well.
What about (1)? This premise just says that God is the best explanation of what grounds moral values and issues moral duties. I like this one because, unlike some versions of the moral argument, it does not require that God be the only possible source of morality (although I think that’s quite correct). This means a skeptic can create whatever mere possibility he wishes; however, that’s not good enough. Is it a better explanation of objective moral values and duties than God? I highly doubt it.
The second premise is more likely to be affirmed. It basically says the best explanation of it seeming to us that moral values and duties are objective is that they are, in fact, objective. This means that mere possibilities, like the possibility of being mistaken or the epistemic possibility of God’s not existing or any number of things won’t work against this premise, unless one has an argument or belief that is rationally and justifiably held stronger than the belief that one seems to have objective moral values and duties.
So what good is this argument? Well, I’m not so sure it will convince the skeptic or atheist. He may be glad to dispute the first premise, or the second, but it will be difficult to do so without engaging in question-begging. In any case, I don’t think this argument is primarily meant to convince of God’s existence; it is primarily meant to convince that it’s perfectly justifiable to believe in God’s existence. And if such a belief is perfectly justifiable, then not only are Christians in a good spot, but non-Christians do not have the recourse that they would believe if only it were justifiable. What do you think, whether about the argument and/or its goals?