This is a tricky concept, what exactly is God's relation to time? There are two types of eternity, either is problematic when considering God's nature. Does God exist outside time and timeless meaning the whole of created time is one and the same to God. He can view the past and present and future simultaneously. He views time from outside of it eternally. The problem here is that God cannot therefore act in time , react to prayers,save humanity or do anything at all ! If on the other hand he is eternal in the sense of being in time, he travels along with the forward time motion of the Universe but He will go on forever, He then would be restricted to what powers he has, and this is not what most Theists believe.