Why would God punish someone forever?

One way to understand the justice of everlasting damnation is to think of hell lasting forever because the damned make it that way. They forever continue to sin and merit exclusion from God.

Think of it this way. If you’ve ever been around a self-centered person, you know he finds it excruciating to be in the presence of a person everyone else admires more than they admire him. The damned in hell may even love themselves and their sins so much that the selfless love of God may be unbearable to them. They may even choose to remain in hell, thinking it is better than heaven.

Moreover, if hell were temporary, it would be incredibly unjust. Since heaven includes eternal bliss and happiness with God, then no matter how long a person spends in hell it will seem like only a few seconds compared to the infinite happiness that awaits them in heaven.