“That certainly is an interesting way to put it. Do you know the source of that quote? I tried to google it and all that came up was FreeRepublic. :)”
I’m not surprised. Its buried someplace in “The Pedallion” and I doubt that’s on line. It may also be referred to in the “Ante Nicene, Nicene and Post Nicene Fathers”. Its almost a cliche in Orthodox seminaries and is generally thrown out to first year students to shock them.
The meaning is that God, as the author and creator of “existence” does not, by definition, “exist”. The concept becomes very important in Trinitarian and Christological theology as I suspect you can imagine. Its also the reason why Orthodox theology tends to be apophatic, which is to say it describes God by saying what He is not.
I still puzzle over that one. :) Why can't we just say that God is the author and creator of everything ELSE that exists, but not Himself? I would think that God exists because we can say for sure that there is that which is God (concretely, more than a mere idea) and there is that which is not God.