"Does philosophy and science work together to offer compelling evidence for the existence of God?"

Pro says that his first premise is the only premise that can reasonably be challenged. Actually, the first and second premise can both be reasonably challenged because they are the same premise. The first premise states it in our ordinary vernacular; the second premise says the same thing using possible world semantics.There is not really enough meat in Pro's presentation to make sense of this argument. For example, he doesn't define maximal greatness. Nor does he explain why the third premise is true. Thankfully, I am familiar enough with this argument to fill in the gaps.Alvin Plantinga, who made this argument popular, defined maximal excellence as being all knowing, all powerful, and wholly good. Maximal greatness means having maximal excellence in all possible worlds. That's why if a maximally great being exists in at least one possible world, then it exists in all possible worlds, including the actual one.This argument may be sound. The problem is that it's impossible to say. So the argument can't be shown to be sound. Let me explain the difficulty.If it's true that there is a possible world in which maximal greatness is instantiated, then there can't be any possible world in which maximal greatness is not instantiated. The reason is because if it's instantiated in one possible world, then it's instantiated in all possible worlds. But that also means that if there's a possible world in which maximal greatness is not instantiated, then maximal greatness is not instantiated in any possible world. The reason is because if it were instatianted in any possible world, there wouldn't be a possible world in which it's not instantiated.So whether you arrive at the conclusion that a maximally being exists or does not exist depends on whether there's a world in which maximal greatness is instantiated or a world in which maximal greatness is not instantiated. So before we can say whether the ontological argument is sound or not, we first have to evaluate which of these premises is true.Premise 1: There is a possible world in which maximal greatness is instantiated.Premise 2: There is a possible world in which maximal greatness is not instantiated.If premise 1 is true, then premise 2 is false. If premise 2 is true, then premise 1 is false. If you try to refute one of the premises by assuming the other, then your argument begs the question. So how can you go about adjudicating between these two premises?Well, there just doesn't seem to be any way to do that. The temptation might be to say that as long as there's no obvious incoherence in a world, then that world is possible. But the problem is that there's no obvious incoherence in either possible world in either premise. It is only be assuming the truth of one premise that the other world becomes impossible, which again is to beg the question.Since we cannot know which of the two premises is true, we cannot know if the ontological argument is sound. And if we can't know if the ontological argument is sound, then the ontological argument cannot serve as a rational justification for belief in God.Alvin Plantinga himself seemed to recognize this. In his book, God, Freedom, and Evil, p. 112, he says,"But obviously this isn't a proof; no one who didn't already accept the conclusion, would accept the first premise. The ontological argument we've been examining isn't just like this one, of course, but it must be conceded that not everyone who understands and relfects on its central premise--that the existence of a maximally great being is possible--will accept it. Still, it is evidence, I think, that there is nothing contrary to reason or irrational in accepting this premise. What I claim for this argument, therefore, is that it establishes, not the truth of theism, but its rational acceptability."That's a pretty low bar for a debate on the existence of God. Basically, all Plantinga thinks the argument establishes is that it's not irrational to be a theist, but to win this debate, Pro needs to show that theism is true, and Plantinga doesn't think the ontological argument does that.