The Modal Ontological Argument

I will be arguing Pro for the Modal Ontological Argument, which is Christian philosopher Alvin Plantiga's version. The argument is as follows. . Definition of God: I am arguing in favor of the traditional monotheistic God, which is a being that has certain attributes. These attributes are omniscience (all knowing), omnipotent (all powerful), omnipresent (present everywhere at any time), and omnibenevolent (morally perfect). These attributes are called "great making" properties, as "greatness" is typically correlates with power, presence, and sometimes character. This being is also supernatural and eternal, whose existence is necessary. From this point on, we will call God a maximally great being (MGB). 1. God, by definition, is a maximally great being that exists necessarily (based on traditional definition). 2. It is possible for a maximally great being to exist in some possible world. 3. If it is possible for a maximally great being to exist in some possible world, it follows that it is possible for a maximally great being to exist in all possible worlds. 4. If it is possible for a maximally great being to exist in all possible worlds, then it is possible for a maximally great being to exist in our world (in reality). 5. Based on 1-5, a maximally great exists in all possible worlds (including our world) 6. Conclusion: A maximally great being exists. Explanation of #1: Just gives the generic definition of the traditional monotheistic God. Either such a being exists, or such a being doesn't exist. Law of excluded middle: {either A or B, if not A, then B, if not B, then A. } Explanation of #2: Simply means that we can imagine a world at which a maximally great being could exist. If such a being "could" exist, then its a least possible for it to exist. Explanation of #3: A maximally great being cannot exist in some worlds and not others. If a maximally great being exists in a world that we know nothing about, then a maximally great being must exist in all and any world that we know nothing about. Explanation of #4: Logically follows from #3, if a maximally great being must exist in all possible worlds, including possible worlds which we know nothing about, then this maximally great being must exist in our world (reality), since our world is included amongst the "possible worlds". Explanation of #5 and #6 (Conclusion): Therefore, God exists in our world as a living reality. Since my opponent immediately jumped at the opportunity to accept this debate challenge, I will assume he has at least a novice understanding of modal logic. With the many characters that are remaining, I will give a brief sketch on what is meant by "possible worlds". We can think of possible worlds semantics as a way to describe the way things could have been. For example, if I say "There is a possible world at which Barack Obama will not be President of the United States". That just mean that Barack Obama could have easily NOT been elected as President under right circumstances. So he is President in world A, but he may not be President in world B, or C, D, etc. His presidency is contingent on him getting elected, but every circumstance is not equal, so while he may be President in our world, in another world he may have been caught in a scandal and thus not elected, he may have died unexpectedly and thus not elected, he may have quit the race and thus not elected, or he may have been elected and became President as he did. So all of these are "possible worlds"/"possible scenarios" at which things may have been different. So if you tie that line of reasoning in with the argument, you will see where the argument is coming from. So now the argument is officially made, and I will patiently wait on the response from my opponent to see his objections and refutations. Good luck.