Archeology does offer some very promising new pieces. Though part of the problem is that those pieces tend not to fit very well into what the majority of people studying the field professionally want to see, so there’s undue focus on things they think they can tie into the narrative as it stands and far less on the things that offer a quite different narrative entirely. But given enough time, I think it will sort itself out.

As for the concept of salvation predating Jesus, arguably the even more interesting question is just what picture of salvation Jesus was actually pitching. There’s a common assumption that Jesus as depicted by the canonical texts is a faithful approximation of the historical figure’s theology, but while this is often taken for granted, it seems extraordinarily unlikely that the surviving tradition passing the filter of Jewish persecution and then later Roman acceptance is the unadulterated representation of the guy who allegedly upset both factions enough he was killed for it.

So most consideration of Christian concepts has this inherent anchoring bias around all the details of modern Christianity that are inescapable in the western world.

But we’re dealing with a tradition where literally the earliest texts are letters from a guy who is known to have been persecuting followers of Jesus writing to communities outside the areas he would have had authority to persecute, swearing he’s not lying about having joined the movement while simultaneously telling people not to pay attention to any other versions of Jesus or gospels than the one he offers them and to give him money.

He advocates a tradition based on the authority of Peter, the guy whose own tradition constantly has him missing the point of teachings or arguing with Jesus, and who is unanimously agreed in texts to have been denying Jesus 3 times concurrent to the ~3 different trials to condemn Jesus. In some Peter even goes back into the guarded area where one of the trials is taking place.

If this wasn’t a global active religious tradition, but instead a murder mystery, might we not want to be a bit skeptical of the guy seen fighting with him who was publicly denying him around the time of his trial and arrest or the guy persecuting his followers who suddenly joins them claiming he couldn’t see and then miraculously could after communicating directly with their dead leader? But no, it’s all fine because a rooster crowed.

When you look beyond cannon, there’s wildly different versions of a lot of the concepts in canonical Christianity.

For example - don’t you think it’s weird that an “only child” of God would constantly be referring to those around him as his brothers and sisters? That language seems inherently at odds with the canonical exclusivity of Jesus’s literal divine parentage, but seems much more in line with concepts like those found in the Gospel of Thomas, such as:

When you know yourselves, then you will be known, and you will understand that you are children of the living Father. But if you do not know yourselves, then you live in poverty, and you are the poverty.

Or

Jesus said, "If they say to you, ‘Where have you come from?’ say to them, ‘We have come from the light, from the place where the light came into being by itself, established [itself], and appeared in their image.’

If they say to you, ‘Is it you?’ say, ‘We are its children, and we are the chosen of the living Father.’

This notion of recognition of one’s own divine parentage in that work then fits into its depiction of salvation as a birthright:

Jesus said, “The messengers and the prophets will come to you and give you what belongs to you. You, in turn, give them what you have, and say to yourselves, ‘When will they come and take what belongs to them?’”

Further played out in parable form:

Jesus said, “The kingdom is like a person who had a treasure hidden in his field but did not know it. And [when] he died he left it to his [son]. The son [did] not know about it either. He took over the field and sold it. The buyer went plowing, [discovered] the treasure, and began to lend money at interest to whomever he wished.”

This picture of salvation as an inheritance for each individual effectively removed the priestly business of getting people to hand the authority over their salvation over to you in order to lend it back out to them at interest. A massive business at the time.

If you were Jewish and you committed sin, you were supposed to go to the temple, buy animals to sacrifice, and bring them to the priests to eat and burn. As well as regularly pay the temple to keep up these functions.

Canonically, Jesus kicked out the people selling these animals from the temple, but you might notice that it’s only in Mark that he tells people to stop carrying offerings through the temple when doing so. That part goes missing in the ones copying off it, I suspect because of the timeline issue of prohibition of sacrifice before he’s allegedly taken the symbolic place of sacrifices.

But the admonishments against any kind of sin sacrifice seem again more in line with extra-canonical Jesus’s stance on sin, such as:

His disciples asked him and said to him, “Do you want us to fast? How should we pray? Should we give to charity? What diet should we observe?” […]

Jesus said to them, "If you fast, you will bring sin upon yourselves, and if you pray, you will be condemned, and if you give to charity, you will harm your spirits.

The attitude therein, of “Don’t lie, and don’t do what you hate, because all things are disclosed before the truth” seems more akin to the attitudes in Corinth pre-Paul of “everything is permissible for me” even if Paul was correct that not everything is beneficial.

The canonical Jesus has an emphasis on the body such that there’s a Eucharist to become one with him by drinking his blood and eating his body. In Thomas there’s a radically different approach where it is by drinking in his words and ideas that one becomes like him and sees as he did.

But this version of Jesus didn’t magically find its way on top of the table at Nicaea, and instead ended up buried in a jar for centuries because simply possessing it was a death sentence, and the version of it that was preserved is distanced enough from a historical figure that it’s again like reconstructing wet shredding.

So while it’s likely that a historical Jesus existed, what he was actually pitching regarding salvation is largely a mystery. But the canonical depiction of it has serious issues when considered without anchoring bias, and there was a wide array of alternatives that differed quite significantly from the canonical claims.

All that said, I agree that diving into a secular analysis of the Bible is pretty effective at reducing the hold of indoctrination. Like people indoctrinated with absolute terror over the influence of Satan might be pretty surprised to find that the whole concept probably draws from fanfiction following a lazy adaptation of a polytheistic story in the opening of Job where a goddess’s name was replaced with the generic term ‘adversary’ (Satan) in petitioning the head god to kill the child of the protagonist (as the goddess Anat petitions El in the earlier Canaanite A Tale of Aqhat). The Israelites were polytheistic for centuries until later monotheistic reform, so a lazy adaptation of Job to monotheism may have left a supernatural ‘adversary,’ and suddenly people became obsessed with the idea to the point of eventually burning their neighbors alive trying to hunt it out.