Eternal existence

Theists say that God is eternally existent. Some theorists take this to mean that God is timeless--categories of past, present, and future just do not apply when we are talking about God. Others hold, instead, that "eternal existence" means that God exists at all times. In other words, if God is eternally existent, he has already existed for an infinite amount of time, and he will continue to exist for an infinite amount of time--his existence never began and will never end.

About the latter concept of eternity, it is common to observe that we finite human beings cannot really conceive of the infinite. If that were the case, then we could not understand what God's eternity was; an eternity is an infinite amount of time. But others say we have some notion of an infinity--of at least a potential infinity. The idea is that we do have the notion of a series that begins and has not ended. A series of moments that has begun and not ended is potentially infinite. But is this notion full-bodied enough for us to have an adequate conception of God's actual infinity?