Robin Parry’s (aka, Gregory Macdonald’s) book The Evangelical Universalist examines whether or not Jesus believed in an eternal conscious hell and, by the time he’s done, he suggests there is a text that might suggest Jesus moved in a universalist direction.
Gehenna, Parry argues, did not refer to the garbage dump outside Jerusalem but was an image from the prophets for a place of destruction and burning. Thus he refers to texts like Isa 30:33 and 66:24. Gehenna for Jesus meant a place of condemnation and a place to avoid at all costs. In fact, Parry argues that the concept of Gehenna was not a clear concept at the time of Jesus: it meant punishment and fire.
So, he goes to the two major Gospel texts: the parable of the rich man and Lazarus (Luke 16) and the “eternal life/punishment” in the parable of the sheep and goats in Matt 25.
On Luke 16: he sides with Powys to say the parable is not about what hell is like but about taking a Pharisaic sense of the world to come, automated judgment, reward and punishment as well as Gehenna. Its purpose was to call the Pharisees to repentance and it subverted typical Pharisaic ideas. It is therefore unwise to infer anything about the after life.
On “eternal punishment” in Matt 25:46 he takes the typical line: “eternal” means “the age to come” and it therefore describes the sort of punishment one experience in that time period, but it says nothing about how long the punishment will endure.
He also appeals to the rhetorical intent of hell texts: to warn people to change and to warn of judgment.
Mark 9:42-50 has a powerful statement about salting with fire and Parry sees that expression referring to the purifying fire (almost a purgatory idea) instead of an endless retributive fire. He’s not certain, however