Mankind has invariably looked upward throughout history in the belief that God lives "up there". However, "up" is a very different place depending on where on earth you happen to be. Point is... common belief is that God lives somewhere other than earth.
A "year" is a man-made concept describing the time it takes our insignificant little speck of rock to make a single revolution around our insignificant little star (the sun). It is an arbitrary measure of time in the grand scheme of things, and it is presumptuous of us to assume that one who has a hand in the grand scheme would measure time in the same way that we do.