The Ontological Argument

[Locke]

It is possible that the greatest a being can actually be is less than maximally great. (That is, it is possible that a maximally great being cannot exist.)

Thus, there is a possible world in which a maximally great being cannot (and therefore does not) exist.

Thus, no being can be maximally great, since being maximally great involves existing in all possible worlds.

That's just playing within the boundaries of modal logic. If we're going to deal with reality, possible worlds don't exist. Only the actual world exists. The concept of "maximally great" is incoherent in the face of reality and it becomes plainly obvious that he's attempting to define God into existence by insisting it must exist in all nonexistent and existent worlds.

Actually in the face of reality 'maximally great' makes perfect sense, considering that out of everything that exists, something has to be the greatest. If two things are exactly equal and greatest then they are both the 'maximally greatest'.

Maximal: The greatest or highest possible.

I'm going to try to help clear the water some of you seem to be drowning in. Before you engage in a logical debate you need to understand a core principle - if you don't get it, just stop.

There are absolute and relative impossibilities. FOR EXAMPLE, it is relatively impossible for a man to lift a car over his head, because he simply isn't strong enough. Sure, it can be imagined, but by the laws that govern the universe it is relatively impossible.

Something that is logically impossible is considered absolutely impossible. These are things that are impossible by definition. They require a violation of logic and truth, thus invalidating the argument. Examples of absolute impossibilities would include things like loud silence, or a 19-ounce pint.
Make sense?
No logical question has proved God doesn't exist. In fact, most such questions fail to account for God's true nature, so they ask an irrelevant question anyways.
Suffice to say, logic cannot prove the existence of God.. nor can it disprove it.

@ the billion dollar word substitution: A billion dollars is not omnipresent, and thus in a possible world it could either be nonexistent, or displaced, or you might not even have a bank account or exist in the first place. The argument does not work for the billion dollars where it does work for God because God was defined as omnipresent. But again, logic games will never prove a point either way; they only prove the limits of an individual's ability to see beyond what they wish to be true.

@ the triangle argument: A triangle is, by definition, a plane figure with three straight sides and three angles.

Go read a book.