Is Hell eternal?
We are brought into this earthly world as eternal beings. Our life here is simply a stop in God's plan.
We cannot, with our human minds, even begin to get a glimmer of what Heaven and Hell are really like. The only thing that we can comprehend, if we are willing to, is that each and every single one of us is created by The Father. His wish is that "none of us should perish, but that all receive the Kingdom."
However, because of that great love that the Father has for us, His children, He gives us free will. The term "free will" is thrown around regularly by Christians. My take on what that really means is this: The reason that humans pro-create the way we do is so that we may have some small, miniscule idea of what we mean to God. As much as we love our children He loves us, plus infinity.
That loves keeps God from being able to control our will; just as we want our children to come to us willingly and lovingly, God wants us to come to him that way. He has given us the choice.
We have two of them...Heaven or Hell. It's that simple and it is "forever" because God is forever. He doesn't send anyone there; we choose our final home. Hell has to be forever because Heaven is forever. What would be the reason for anyone to choose Heaven if we knew we would eventually "get out" of Hell? Hell is a natural consequence of a choice we make.