Let me first explain my understanding of these words (punishment & revenge):
Punishment is typically when you do something to one person to make things better for society, or for that person. It is either something unpleasant, so that the person will not want to do the bad thing, because they know the punishment is there, or they do the crime, but because of the punishment (death penalty / chopping off someone’s arm / being locked away) they cannot do the crime again or will think twice before doing it again.
Punishment, in theory, serves the majority of people. It is a good thing. It has positive benefits to most people (negative to one person – the crime committer – temporarily to solve a social problem).
Revenge is completely different. That is when you cannot control your anger and hurt someone because they hurt you. No positive benefit, other than making the angry person feel better. It is, as I understand it, all about emotions.
Romans 12:19: “It is mine to avenge, I will repay, says the Lord”. Hell does not seem like punishment, it seems like revenge. This makes no sense, given the "good" and "just" descriptions of God.
So, based on the above, what is God, who is good and just, intending by sending people to hell: to punish, or to take revenge? Please include a logical explanation with your answer.
EDIT
I've been asked to define what I understand as "hell", and the doctrinal context that I want this answered in, so here's my attempt to do that:
I understand hell to be a place of eternal suffering that God created, where He sends people who do not believe in Jesus.
This is what I understand to be the typical protestant view of hell, as described in the bible. If you have a different view, then you may not be the best person to answer this question, because I really want an answer from those who believe this point of view.
I would also like all answers to include some kind of reference, if their source is not simply logic.