Kolasis can mean "punishment". A punishment of final death would be everlasting. But I am eisegeting, which is poor form. I read what I want to read. Why am I doing that? Because I cannot say, "Credo in un Deo crudel", ("I believe in a cruel God").
I asked what the purpose of eternal torment is. It is not rehabilitative. It is not a deterrent, especially if one believes that Man has not the capability of not sinning or of believing in a savior. It is punishment for its own sake. After how many years until justice becomes cruelty? 100? 1,000? 1,000,000? Remember also, that some of your family, friends, neighbors, co-workers, et. al. will not be saved. Can you watch them be tortured and remain sane? God gave me the ability to empathize, and I can't just turn it off. I remember what it was like to be lost. I can't just say, "They can all go to Hell for all I care, as long as I'm saved". This is what we're defending in the name of doctrinal purity.