Abraham your father rejoiced that he might see my day: he saw it, and was glad.  The Jews therefore said to him: Thou art not yet fifty years old, and hast thou seen Abraham?  Jesus said to them: Amen, amen I say to you, before Abraham was made, I am.  They took up stones therefore to cast at him. But Jesus hid himself, and went out of the temple.
John 8: 56-59
Father Barron has a magnificent article in Catholic World Report in which he explains why it is improper to think of God as a Supreme Being:
Now to God’s invisibility. One of the most fundamental mistakes made by atheists both old and new is to suppose that God is a supreme being, an impressive item within or alongside the universe. As David Bentley Hart has argued, the gods of ancient mythology or the watchmaker God of 18th-century Deism might fit such a description, but the God presented by the Bible and by classical theism has nothing to do with it. The true God is the non-contingent ground of the contingent universe, the reason there is something rather than nothing, the ultimate explanation for why the world should exist at all. Accordingly, he is not a being, but rather, as Thomas Aquinas put it, ipsum esse subsistens, the sheer act of to be itself.
Thomas goes so far as to say that God cannot be placed in any genus, even in that most generic of genera, namely, being. But all of this must imply God’s invisibility. Whatever can be seen is, ipso facto, a being, a particular state of affairs, and hence something that can be placed in a genus, compared with other finite realities, etc. The visible is, by definition, conditioned—and God is the unconditioned. I hope it is clear that in affirming God’s invisibility, I am not placing limits on him, as though he were a type of being—the invisible type—over and against visible things, a ghost floating above physical objects. The invisible God is he whose reality transcends and includes whatever perfection can be found in creatures, since he himself is the source and ground of creatureliness in all its manifestations. Anything other than an invisible God would be a conditioned thing and hence utterly unworthy of worship.
Go here to read the rest. God is I AM, and it is only through His will, and His will alone, that we are. Our existence and that of the universe is a manifestation of the love of God. He called us from nothingness to partake in His existence for purposes of His own. Debates about the existence of God have always therefore struck me as ironic. Men might better debate why they exist rather than pretend that matter and energy can be created ex nihilo except by a God who desires to create.