Hell is our word for “gehenna” which was the refuse dump outside of town where the gases fueled a fire that burned day and night, and “little critters” fed upon the garbage. The image of eternal flames and torment may be figurative, meant to indicate a place or “state of being” that is like living at the dump, for ever.
Think of the various poor souls we witness living on the streets owing to a lifestyle of drug and/or alcohol abuse or prostitution, etc. They often suffer disease, they are dirty, often isolated and angry, sometimes even a little “insane” due to the life/lives they lead. Often they are content to stay that way as long as the money or drugs or alcohol is there to feed their addictions/lifestyle. Even if they are discontented there is often the despair of not having the will or the means to change their state or the fear of being rejected. We should rejoice with anyone who finds the will to lift themselves out of that life by God’s grace. We are all former “pagans.”
C.S. Lewis once wrote that the gates of hell are locked from the inside. This is akin to the alcoholic on skid row or the addict/prostitute that prefers their state of life as long as they get the alcohol, drugs, etc. In hell, I suppose, the rebellious get their “self,” and have no desire than to experience that for ever.
But why eternity in hell? It has to do with the nature of the act (of sin) and the object of the rebellion. Think first of Jesus on the Cross—“My God, My God, why hast thou forsaken me?” In the Mystery of the Father’s “turning away” from the Son is revealed the effect of the first sin: Lucifer’s primeval rebellion. As Catholics and Christians we believe that the Blessed Trinity exists in an eternal state in Communion of Infinite Love (God IS Love). It has been stated that the Father freely gives this Infinite Love (Himself) to the Son eternally and infinitely, which the Son freely and infinitely accepts and returns infinitely and eternally to the Father; and, this Love is the Holy Spirit.
Now what is the effect of Lucifer’s rebellion? My thought is that it caused a temporal “veiling” of the eternal gaze of infinite Love with anger at Lucifer’s rebellion (“In a little moment of anger I hid my face from thee; but with everlasting kindness I will draw thee . . .”). Anger had never before been “experienced” by God, even though He eternally knew that it would occur at the “moment” of Lucifer’s rebellion (perhaps the first "moment’. But I digress). This temporal veil of anger over the gaze of infinite Love was infinitely valuable because of the nature of the Love being “interrupted.” All three Persons “experienced” the temporal interruption of an Infinite Love with a veil of anger, so the rebellion, although a temporal and contingent fact, carries eternal consequence (owing to the “Object” of the rebellion–which is God).
Now, here on earth it is the same. Our temporal acts of sin are acts of communion with the eternal rebel and interrupt the communion of Infinite Love which we were created to enjoy with God (" . . .he has made us partakers of the Divine nature"). As such, our temporal acts carry the same infinite value(whether acts of charity, which is communion with God’s love, or acts of sin, which is communion with Satan’s rebellion) and the same eternal consequences.
We can turn the question over: Why is Heaven eternal? Because of the Object of communion–God. By sin we enter into eternal communion with Satan’s rebellion, just as by entering into communion with Christ’s Cross through the Sacraments we are reconciled to God and restored to the communion of Infinite Love, whereby we are made partakers of the Divine nature.
That’s my view, anyway. I hope it helps.
All my best . . .
Why couldn’t God just deny those who committed serious sins the beatific vision but still allow them to live immortally on Earth? They would never experience the perfect joys of Heaven, but they wouldn’t be tormented forever.