[This excerpt should be read after this one.]
If there were such a thing as a loneliness that could no longer be penetrated and transformed by the word of another; if a state of abandonment were to arise that was so deep that no “You” could reach into it anymore, then we should have real, total loneliness and dreadfulness, what theology calls “hell”. It denotes a loneliness that the word love can no longer penetrate and that therefore indicates the exposed nature of existence in itself.
In truth—one thing is certain: there exists a night into whose solitude no voice reaches; there is a door into which we can only walk alone—the door of death. In the last analysis all the fear in the world is fear of this loneliness. From this point of view, it is possible to understand why the Old Testament has only one word for hell and death, the word sheol; it regards them as ultimately identical. Death is absolute loneliness. But the loneliness into which love can no longer advance is—hell.
Christ strode through the gate of our final loneliness; in his passion he went down into the abyss of our abandonment. Where no voice can reach us any longer, there is he. Hell is thereby overcome or, to be more accurate, death, which was previously hell, is hell no longer. Neither is the same any longer because there is life in the midst of death, because love dwells in it. Now only deliberate self-enclosure is hell or, as the Bible calls it, the second death.
The door of death stands open since life—love—has dwelt in death.
— Joseph Ratzinger, Introduction to Christianity, II.II.3