I was just thinking .... if Hell is complete separation from God, then God is not omnipresent.
— Dan Barker (@DanBarkerFFRF) October 14, 2013
It brings up an interesting but ultimately vacuous point. Barker thinks about hell too literally. Hell isn't a "place". As a non-physical dimension, we must understand it as a "place" only in a metaphorical way, because our own physical understanding of space is bound to be only loosely allusive to the type of "location" that is hell ( if it is allusive at all). Hell simply represents spiritual death and impotence and it is perfectly natural to suppose that God cannot "inhabit" death. Nor is the idea that God is not present in evil or sin damaging to the claim of his omnipresence. More nuanced and less over-simplified thinking about the doctrine of omnipresence is needed.