The Ontological Argument - valid or debunked?

[Esquilax]

When Anselm first wrote this argument, he was careful to distinguish between what we could think of as the greatest possible being and God is the greatest being possible, that is to say, it is impossible for there to be any being greater than God. Your infinite regress is a result thinking of God simply as the greatest being there is. 

Trouble is, there's still no cap on greatness. I get that you're stuck in this mindset, due to the vague nature of your argument, where god's just the greatest thing ever, but your argument is attempting to show that god exists, and extant things have verifiable qualities, that's just the nature of reality, and unfortunately for you, your argument posits that god exists in this world. Actually think about the premises of the argument and the conclusions that follow on from them, don't just be happy that in them your god exists and stop there, really consider the real world as depicted in that argument: god exists, he's the maximally great being. What are his characteristics?

You aren't talking about some airy-fairy philosophical nothing anymore when you reach the conclusion of the ontological argument, you're talking about a real, extant being, and therefore he must have qualities that can be described. He is a set entity, an objective quantity, and to accept that he exists you must have some idea of what he even is. If you don't then I'm sorry, but you're not discussing a real thing, you're discussing an amorphous cocktail of ever-expanding traits with no bearing on reality.

But if god is real, which is the thing you're trying to prove, then he has a set level of greatness that you are asserting to be the highest possible level of greatness, and which I am capable of positing a being greater just by adding to the first being's qualities dominion over that first being. What then? If you're talking about a real entity then your god is no longer maximally great because there's a possible being greater, and that being doesn't exist, putting the lie to the ontological argument. If you're just going to assert that that being I made up is now god by dint of being greater than the one you think exists, then congratulations, you're no longer discussing a real being at all but just vague theological generalities that don't behave like existing things need to, and you're certainly not discussing the actual christian god. Either way, the ontological argument fails.

There is, of course, the third option, which is the one I suspect you're using, which is just to lazily assert based on nothing that the maximally great being under discussion is just the greatest thing there is possible to be, in the process ignoring the dual facts that greatness is a subjective criteria and that no such upper bound on greatness even exists... and in that case I don't really need to take your position seriously: it's nothing more than a bluff, an assertion made without evidence that ignores everything that has been said prior and is completely circular. It's just "god is the greatest possible being because there can be no greater being than god."

It's the same as saying nothing at all.