Omnipresence is one of God’s attributes. As I argued in an article at The Institute for Biblical Studies, however, this property is not essential to God’s nature and should not be understood in spatial terms. God is not a spatial being, and thus He does not exist anywhere, similar to the way in which we should not understand God’s eternal existence to mean He existed before creation. “Before” is a temporal concept, and since time began with creation it is meaningless to speak of anything before creation. Instead, we should speak of God’s existence without creation.
Similarly, as a non-spatial being God cannot exist in any spatial location. To think of God’s omnipresence in terms of occupying points in space is a category error, similar to saying the number seven tastes delicious. To say God is omnipresent refers to God’s cognizance of and causal activity at all points in the spatial dimension.