A Bad Argument for Theism

In general, I like arguments for theism. The ontological argument raises fascinationg issues regarding necessity and existence. The cosmological argument may even be sound. But there is one popular argument that I think is just dreadful. This is the argument from morality. I guess it goes something like this:

(1) There are objective moral truths
(2) The best (or maybe only!) way to understand how such truths exist is by supposing there is a God
Therefore, God is likely to exist

That is the rough idea. The key claim is that objective morality makes likely the existence of a deity.

I wonder if proponents of this argument would also accept:

(1) There are objective mathematical truths
(2) The only way to understand how objective mathematical truths exist is to accept the existence of a deity
Therefore, God exists

I guess there are an infinte number of arguments like this--put whatever you want in between "objective" and "truth" and you get some kind of weird theistic argument.

Of course if one agrees that a Divine Command theory of Morality is true, then there is a direct link between moral truths and God. But if DC theory is true, then we don't really have objective morality. We have a variety of subjectivism in which the only subject that matters is God.

There are more subtle versions of the DC theory that somehow relate Divine commands to our obligations while at the same time allowing the objective moral quality Good to be a real property and not just a matter of divine whim. If God is good, then we don't have to worry about God getting all crazy on us with insane commands. But if God's goodness determines the content of the command, then we have escaped the DC theory. If God's goodness does not determine it, then there is still the element of whim.

If we jettison divine command and argue that God's existence grounds morality because of God's nature in instantiating goodness, then, again, God's existence is connected to morality. But if goodness is a genuine property, it does not need God to be instantiated. If there is a God, God will be supremely good, and that's important. But God's existence is not required to support the real existence of moral properties like good or bad.