I agree on John 10:‘17. However, Gehenna was / Is a real place in Israel with a rich history dating back to Solomon. It is a physical place where not only normal folk, but also Kings of Israel offered their children to the fires of Molech and Chemosh. These were brutal murders of their innocent children being burned alive. Imagine the screams of an innocent baby being rolled into the belly of a red hot idol with its arms stretched out to receive the child. Imagine the screams of a mother watching their child be burned alive.
Now, Imagine what type of person would willingly place a child in the red hot arms of an idol to be burned alive. A person who’s ears were deaf to the screams of that child and blind to the pain it was causing on that child.
Now, imagine a mother doing the same. One that not only willingly, but joyfully offering up her own child.
This is what hell looks like on earth. This is exile. Exile is when God removes one from his presence and from the land. It is not only a physical state, but it is also a spiritual state. When we die, we either remain United with Christ, or exiled.
Because of this, I have a very difficult time grasping Gehenna as a metaphor. I see it more as not only a current state, but also a future state. We either remain in our sin (lives of hell) or we turn from our evil ways and follow the ways of God.