This is the best explanation of why there is a hell I've encountered. I've heard the descriptions of separation from God, the pain of loss and great suffering. But the idea of why still never hit home until I read what F.J. Sheed had to say about it. I think sometimes we forget with God that many things are a mystery, and we must always keep this is mind. If there wasn't the mystery, we would have to wonder where faith fits in our life. But Sheed points out that when one dies loving themselves (a selfish love) to the hatred of God, what is God to do with this individual. God lets him/her go to their own place. At least that is the way I understand Sheed's point. God's creation of hell comes down to their desire to isolate themselves from His love. Obviously he/she can't be in heaven because that would mean close union with the God he/she hates. I guess in a way the individual creates their own hell. Or maybe chooses hell would be a better statement.
The above also brought home to me the fact that no matter how I've ever tried to justify sinning, the reason I've sinned each time comes down to one thing. That being my own selfishness. Self is the seed of every sin that takes root and flourishes. Thankfully we're told - be not afraid! We have a merciful and loving God, who sent us a Savior and Holy Spirit to guide us to the light of His truth.