From Ligon Duncan's Fear Not!

It is a surprising thing to note, because so often we speak of hell as a place where God is not. Let me, however, say something provocative. Hell is eternity in the presence of God without a mediator. Heaven is eternity in the presence of God, with a mediator. Hell is eternity in the presence of God, being fully conscious of the just, holy, righteous, good, kind, and loving Father’s disapproval of your rebellion and wickedness. Heaven, on the other hand, is dwelling in the conscious awareness of your holy and righteous Father, but doing so through a mediator who died in your place, the One who absorbed the fullness of the penalty of your sin. Heaven is eternity in the presence of God with the One who totally eradicated sin from your life, the Lord Jesus Christ.

Hell is eternity in the presence of God without a mediator. Heaven is eternity in the presence of God with a mediator, the Lord Jesus Christ.