How am I going to use the word 'God'? I will use it as its Hebrew, Greek, or Arabic equivalents were used by Abraham, by Isaiah, and by Job, by John and Paul, and by Muhammad. I am, therefore, not going to use it in the plural, as words translatable by 'god' were used by Aeschylus and by Horace, by the author of the Ramayana and by the Mayans. God, as understood by theists, by Jews, Christians, and Muslims, is necessarily One, the one and only God. Were he not such, he would not be God, for, if he exists, there can be no other who can set limits to the exercise of his powers or who can compare with him as an object worthy of our loving devotion. And so the psalmist could speak of God as a great king above all gods.
I say "if He exists," but, if he exists, he exists necessarily--that is to say, he could not have not existed. And in this he is unlike finite beings who exist and are what they are contingently, that is, they might have been otherwise than they are and they might not have existed at all.
[...]
Theistic belief is not just belief that there happens to exist a being with such and such attributes, a belief such that someone might allow that there is indeed such a being, but then say, "So what? God exists, as do neutrons and coconuts, but I happen to be interested in none of them." Of such a one theists would have to say that he is not using the word "God" as they use it, for to believe that God exists is to believe that there is a being on my relationship to whom depends everything that I do or might value. And this being requires of me unqualified trust and unqualified obedience, so that I cannot be indifferent to claims about His existence and nature. We finite beings would not exist if God had not created us. We would not continue to exist if he did not sustain us. The outcome of our every project and the fulfillment of our every desire depend on him. Or so theists believe.
MacIntyre, Alasdair.
God, Philosophy, Universities: A Selective History of the Catholic Philosophical Tradition. Lanham: Rowman & Littlefield, 2009. 5-8.
