[14:12] So man lieth down, and riseth not: till the heavens be no more, they shall not awake, nor be raised out of their sleep.
Till the heavens be no more - That is, never; for such is the fair interpretation of the passage, and this accords with its design. Job means to say, undoubtedly, that man would never appear again in the land of the living; that he would not spring up from the grave, as a sprout does from a fallen tree; and that when he dies, he goes away from the earth never to return. Whether he believed in a future state, or in the future resurrection, is another question, and one that cannot be determined from this passage. His complaint is, that the present life is short, and that man when he has once passed through it cannot return to enjoy it again, if it has been unhappy; and he asks, therefore, why, since it was so short, man might not be permitted to enjoy it without molestation. It does not follow from this passage that he believed that the heavens ever would be no more, or would pass away.
The heavens are the most permanent and enduring objects of which we have any knowledge, and are, therefore, used to denote permanency and eternity; see Psalm 89:36-37. This verse, therefore, is simply a solemn declaration of the belief of Job that when man dies, he dies to live no more on the earth. Of the truth of this, no one can doubt - and the truth is as important and affecting as it is undoubted. If man could come back again, life would be a different thing. If he could revisit the earth to repair the evils of a wicked life, to repent of his errors, to make amends for his faults, and to make preparation for a future world, it would be a different thing to live, and a different thing to die. But when he travels over the road of life, he treads a path which is not to be traversed again. When he neglects an opportunity to do good, it cannot be recalled. When he commits an offence, he cannot come back to repair the evil. He falls, and dies, and lives no more. He enters on other scenes, and is amidst the retributions of another state. How important then to secure the passing moment, and to be prepared to go hence, to return no more!
https://biblehub.com/commentaries/job/14-12.htm
So what kind of "this life" Jesus did the Christians in 1 Cor. 15:12 follow or invent if not a Fourth Philosopher or someone created to look like one (one who happened to have been executed in a way that I can only recall happening to Fourth Philosophers in the first century CE)?
Of the four sects Josephus mentions, only the Fourth Philosophy altered the oral Torah of the Pharisees. As he notes in Ant. 18.1.4, the Sadducees were "able to do almost nothing of themselves; for when they become magistrates, as they are unwillingly and by force sometimes obliged to be, they addict themselves to the notions of the Pharisees, because the multitude would not otherwise bear them."
[Ant. 18.1.1] Such were the consequences of this, that the customs of our fathers were altered, and such a change was made, as added a mighty weight toward bringing all to destruction, which these men occasioned by their thus conspiring together; for Judas and Sadduc, who excited a fourth philosophic sect among us, and had a great many followers therein, filled our civil government with tumults at present, and laid the foundations of our future miseries, by this system of philosophy ...
As Josephus notes in Ant. 13.10.6:
... the Pharisees have delivered to the people a great many observances by succession from their fathers, which are not written in the laws of Moses; and for that reason it is that the Sadducees reject them, and say that we are to esteem those observances to be obligatory which are in the written word, but are not to observe what are derived from the tradition of our forefathers.
Jesus is presented as similarly making changes to the oral Torah of the Pharisees in Mk. 7:3-5.
Now in holding to the tradition of the elders, the Pharisees and all the Jews do not eat until they wash their hands ceremonially. And on returning from the market, they do not eat unless they wash. And there are many other traditions for them to observe, including the washing of cups, pitchers, kettles, and couches for dining.
So the Pharisees and scribes questioned Jesus: “Why do your disciples not walk according to the tradition of the elders? Instead, they eat with defiled hands.”
So given Jesus' rejection of the oral Torah and his opposition to the Sadducees on the issue of resurrection and that the NT never mentions Essenes, the only sect that fits Jesus' "system of philosophy" is the Fourth Philosophy, since they are the ones who made changes to the oral Torah and believed in resurrection of the dead.
Josephus goes on to say that the Fourth Philosophy was a new kind of Judaism ("which we were before unacquainted withal"), and Jesus' "system of philosophy" is similarly presented as being new in Mk. 1: 27 ("All the people were amazed and began to ask one another, 'What is this? A new teaching with authority!'"!
And their main belief was also that "one from their country should become governor of the habitable earth," which makes me think Jesus was or was thought of as being "one from their country."
Jesus to me (all things considered, but maybe even just in Paul) looks like the kind of Fourth Philosopher Josephus describes in War 2.13.4.
There was also another body of wicked men gotten together, not so impure in their actions, but more wicked in their intentions, which laid waste the happy state of the city no less than did these murderers. These were such men as deceived and deluded the people under pretense of Divine inspiration, but were for procuring innovations and changes of the government; and these prevailed with the multitude to act like madmen, and went before them into the wilderness, as pretending that God would there show them the signals of liberty.
So for me, the NT looks like a collection of writings made by people who acted "like madmen" by following someone who was this kind of Fourth Philosopher. I just don't see any need to invent someone like this when there were "a great many" real people like this.