Does Jesus talk about eternity?
The Greek adjective that is translated as “eternal” is the Greek word, aionios (αἰώνιος). Jesus uses this word in twenty-three verses out of his 1,911 verses recorded in the Bible. In the KJV, it is either translated as “eternal” or “everlasting.” The Greek word literally means “lasting for an age.” There sense is “on-going,” or "perpetual."
This is an adjective form of the word aion, (αἰών) that means primarily "a lifetime," but, derive from that, "age" "generation" or "eon.” This word is usually translated in the Bible as “an age.” In aionios, the Greek prefix a- and suffix -ios often work together like our ending “less.” It appears in the Greek words for “harmless,” (akeraios), “blameless,” (anaitios), and “unprofitable” (achreios), but here that meaning is less clear because the “a” is not necessarily the negative prefix that it can be. It is more part of the word “aion” rather than an “a” of negation. More generally, -ios turns nouns into adjectives. The adjective has the sense of "of an age," “of a lifetime,” or "of an era," but only in the context of a span of time For the living, a "lifetime" is perpetual. We are perpetually alive until we die.
The History of the Word
This word does not mean "forever" or anything like it. It specifically means a limited span of time. Some say that the word aion comes from aei einai, which means "continual being." However "continued being" does not mean "eternal." Other words related to aion, such as the Greek word aidios, which is translated as "everlasting" in the Bible were typically used to mean a period of long, but limited duration. For example, a lifetime stipend is typically described as aidios. We might define it as closer to "perpetual" but, in the case of a stipend, limited by a lifetime.
Aion was used as a measurement like we use "a generation," that is, the space between one generation and the next, which is around thirty years. The word aion can refer to a longer period of time, but it is not the word for "eternity." In modern Greek, this biblical word has become the basis for the Greek words for "eternity," aioniotes (αιωνιότης) and aionioteta (αιωνιότητα) but these words did not exist in ancient Greek. These concepts were taken from the Bible, making their way into modern Greek as they have into modern English.
This confusion started with the translation of the Bible into Latin. In the Latin Vugate, the word aion and aionios were both translated as aeternum. That word originally meant “for an age” and “lasting” as well. However, it also meant “eternal” in a philosophical sense. Rome itself was called “the eternal city” using this term. It is hard to tell, without research, if this change was influenced by the use of the Latin Vulgate for Christian doctrine. Earlier writings seem to use the word to mean “a long time” or “perpetual.”
Jesus’s Use of Aionios
Jesus only uses it in a positive sense in five phrases:
“Everlasting life” (Matthew 19:29, John 3:16, John 4:14, John 5:39, John 6:54, John 5:24, John 6:27, John 6:40, John 6:47, John 10:28),
“Eternal life” (Mark 10:30, John 3:15, John 17:2),
“Life eternal” (Matthew 25:46, John 4:36, John 12:25, John 17:3,),
“Life everlasting” (Matthew 19:29, Luke 18:30, John 12:50), and
“Everlasting habitation” (Luke 16:9).
Notice how heavily this concept depends upon John. Out of the twenty-three verses, fifteen of them are from John. We see a similar imbalance in other common patterns, such as Jesus asking people to “believe in” him (see this article).
He uses it in the negative only in three phrases, each appearing only once.
“Everlasting fire,” (Matthew 18:8),
“Eternal fire,” (Matthew 25:41), and
“Everlasting punishment” (Matthew 25:46).
Notice how exclusively this concept depends on Matthew, but the sample is very small. This was clearly not a major theme of Jesus’s, no matter what its specific meaning.
Nothing else is referred to by Jesus as “eternal” using this word, not the Divine, heaven, the soul, the angels, or his words, which do not pass away. That should give us a clue that the Greek doesn’t mean “eternal” in the way that it is used today.
Jesus’s Teaching
So what did Jesus mean by “eternal life?” The sense seems to be an ongoing life, that is, life after this life. The word translated as "life" means "living" but it also means "substance," "existence," and "property." Read this article about eternal life. Jesus uses it to mean "existence" beyond the single physical life we are living now. For more on how Jesus uses this “life” word with other words about human existence (soul, heart, spirit, etc.), read this article. His use of this word leaves open the possibility of a lot of different forms of future existence, including reincarnation. Indeed, Jesus says reincarnation happened in the case of John the Baptist (Matthew 11:14, Matthew 17:11, Mark 9:12).
However, the idea is clearly that life and our identity can go on in some form after death. He gives some hints about one of those forms (Matthew 22:30, Mark 12:25), and certainly with his own death and resurrection, but he seems reticent to tell us more.
The case for “eternal” punishment is much harder to make. The word is used twice with “fire,” both times describing the fire of Gehenna. But Gehenna was a perpetually burning trash dump outside of Jerusalem. It had burned and would burn for more than a lifetime. It is used as an analogy for punishment, but clearly, Jesus wasn’t saying that people would actually be tossed into that particular trash dump. Was this fire an analogy for perpetual suffering on some other plane? While is possible, he only says that the fire is perpetual, not anyone’s presence in it.
But what about the last line of the Parable of the Sheep and Goats? Matthew 25:46: “And these shall go away into everlasting punishment: but the righteous into life eternal.”
The word “punishment” here is a translation fabrication. The word translated as "punishment" means the pruning of trees. This is the only time Jesus uses it. From this idea, we can get the meaning of "curb" and "restrain," but the idea of "punish" is far off the mark. There is a Greek word meaning “punish,” but this is not it. In the context of the theme of productivity, which is hidden in much of this parable, the term “pruning” is well chosen. Trees are Jesus's symbol for productive assets. Pruning is the elimination of the unproductive parts of the tree. Jesus seemed to have viewed the “pruning” of the fire as the burning away of the unproductive parts of a person. This is a pretty thin foundation for our concept of “hell.”
Conclusion
If we go by Jesus’ words, the idea of “eternal life” and “eternal punishment” is pretty far from his teaching. He certainly taught life after this life, but he never guaranteed that it would be eternal, especially in the sense of changelessness. Could the righteous turn bad in the life after this life? Didn’t some of the angels?
In the next article, we will look at how the concept of “hell” was created much like the concept of “Satan” (see this article) by conflating various ideas and poor translation.
I think it all has to do with reaping what you sow... If your harvest is good fruits you benefit life as it's meant to be from that harvest for that aionios until the next harvest and new aionios, otherwise you need to keep pruning.
You can keep enjoying those good harvests time and again until you sow bad seeds and need to reexamine your actions for where love is not in them. I think that's how to measure aionios.
I'm not convinced it necessarily has anything to do with an afterlife, just the lifespan of love/life or punishment/"death" between our actions and the results of them.
The worst of all bad seeds is hypocrisy and deceit. Bad seeds, bad deeds, disguised as good. Sometimes it's good seeds in others pointed out as bad. Sometimes it's resisting pruning for yourself because you're pointing out somebody else's need for pruning to distract from your own lack of life in this aionios.
...And the worst of the seeds of hypocrisy is blasphemy--claiming bad seeds to be of God and using the name and claimed authority of God to condone bad seeds and/or shame good seeds, to try to avoid pruning/"death"/humility/growing in love, and the effects/harvest of harmful actions/seeds, or to control others.
The funny(-in-sad-way) thing about this is that the things Christianity traditionally teaches assist people in missing out on living their lives that way...
...The idea of aionios being an eternal afterlife, and especially the idea of faith just being "believing in Jesus" as kids "believe in Santa" as though that's a proclamation of Jesus of Nazareth simply not being a fictional character...rather than the faith Jesus talks about: our deeds and walk through life being led by trust/love... Living for the afterlife too often makes people forget to live in faith from aionios to aionios.