What do you think of this argument for God?

[SteveII]

1- It is possible that a maximally great being exists.

"Greatness" is a value judgment. Value judgments are inherently subjective. "Maximally great" is a nonsensical contradiction in terms, even ignoring its complete lack of an actual, coherent definition (it never supplies any way to actually measure "greatness", so it's a complete non-starter).

This is also where the ipse dixit comes in, and why I mentioned bare assertion when examining this premise above. There is no reason to accept that it is possible that a "maximally great being" exists.

While greatness might be subjective, maximal greatness is not.

Unfortunately, this is utterly nonsensical. "Greatness" is not an objective quantity, and no actual coherent method of measurement can be supplied. Simply asserting that "maximal greatness" is not an incoherent concept does not actually make it so. Nor does trying to say that it is objective rather than subjective.

Also note the way that Steve's chosen "real" variation of the ontological argument fits into the condensed version that I supplied at the beginning of this post. "God" is defined as "a maximally great entity"; the rest of the argument, then, is spent trying to show how a "maximally great entity" is defined as existing, without at any point even attempting to establish that a maximally great entity is actually possible. It simply asserts that it is, and expects to be taken at face value.

It's the same issue every time, in every variation of the ontological argument. There is always, at one point or another, a complete ipse dixit moment, whereupon it collapses on its face. And, again, that's without getting into the completely incoherent mess that is the actual premises. This is why the ontological arguments have never been relevant in philosophy outside of theistic circles that refuse to let them die because they're desperate for anything that they can lay their hands on.

The ontological arguments are always, invariably, regardless of specific wording, worthless.

Consider these three premises from Robert Maydole's Moral Perfection Argument:

M1: A property is a perfection only if its negation is not a perfection.
M2: Perfection entails only perfection
M3: The property of being supreme is a perfection of that property.

Maydole defines a perfection as a property which is better to have than not to have and something is supreme if there is nothing which is even possibily greater or as great as.

Suppose that it is not possible (necessarily so or as you say 'nonsensical) that there exists a being with supreme (maximally great) properties . In that case, for any property x, it is necessarily the case that property x is not an example of being supreme. Well, if that is the case then, necessarily, for any property x, if x is supreme, then x is not supreme.

Now suppose being supreme is a perfection (M3) and that only perfection entails perfection (M2).

If these premises are true, and being supreme is not possible, it follows that not being supreme is a perfection. But if we accept M1, it is also the case then not being supreme is not a perfection. Now we have a contradicion: not being supreme is a perfection and not being supreme is not a perfection. Which one do you want to reject and why? If you can't, you must concede that a supreme property is possible and by extension, that it is possible there is a supreme (maximally great) being.

Now, all I have done (with help) has been to summarize the argument. The actual formal logic is 12 steps long. It then fits into the Ontological Argument, which is another 16 steps long. Since you probably don't have my book, you can get a copy of the argument in the link below.

So, it seems your claim of ability to refute the Ontological Argument "in a couple of sentences" is entirely based on your lack of understanding of the argument. Perhaps if you didn't lecture us like a condescending prick, this wouldn't be so funny.  

Adapted from Blackwell Companion to Natural Theology, Wiley-Blackwell 2012 pg. 580 ff. with additional commentary from https://calumsblog.com/apologetics/argum...-argument/ (to help me with some of the symbology)