If God is omnipresent and hell is the absence of God. How can this be?
As morally evil as Satan and Hell are, they have metaphysical goodness. Being and existence are metaphysically good. God isn’t present in His creation as a human being is present in his bedroom. All creation exists in God in that He continually gives it existence. Satan and hell are dependent on God for their existence. They are not outside the scope of His metaphysical influence. But morally, they are diametrically opposed to Him because morally He is totally good.
Fr. Vincent Serpa, O.P.