How to refute the argument that is is possible to be saved without Jesus and do apologetics for it

I've recently thought of an argument that might undermine Christianity but I'm not sure if I simply reinvented a super old argument that already has a refutation or it's a novel one (probably not), but I would like to know if there is any way to refute or counter it (there is also a possibility that I might just be confused about certain ideas or topics so that would also serve as an objection if I misunderstood something in the construction of the argument itself). The argument is as follows: **(1)** It is possible to be saved without belief in Jesus **Proof of (1):** When the Israelites left Egypt and embarked on the Exodus and the Joshua conquests, they had the Tabernacle as the sacred space. Then during the United Monarchy, they had the First Temple. However, there was a 71 year period of exile and Babylonian captivity where there was neither a Tabernacle nor the Temple. This is from 586 BC - 515 BC according to contemporary scholarly accounts. Since God desires us all to be saved and there is nothing preventing Him from that, He would enable innocent people born during this period (keep in mind that the [average lifespan was approximately 52 +/- 15.29](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2625386/#b4) according to Griffin, 2008, which means that there would certainly be people who were born and died without ever having access to a traditional means of repenting and being saved and this is at a time when Jesus has not arrived yet) to repent and be saved if He is all good. Hence, since He is perfect and all-good and desires us to be saved, He would enable us to have an option to save ourselves even without the Holy Temple AND without a Tabernacle. The people who lived during this period as per the logic would have no more or less chance and ability to be saved than anyone born at a later date for God is not unfair and unjust, particularly to those who are innocent. **Supplementary Addition:** In the 'Old Testament', no where does it say that sacrifice (including Jesus sacrificing himself on the cross) is the *only* way to atone for sins. It is not necessarily even the best way in every case. **Conclusion 1**: If it's possible to be saved without belief in Jesus as per (1), then there is no reason to convert anyone to Christianity specifically. **(2)**: Because the Necessarily Existing Being (God), also known by terms such as *Ipsum Esse Subsistens*, *Actus Purus*, Unconditioned Reality, God of Abraham, Isaac and Jacob, etc. never does anything unnecessary or arbitrary for that would entail a definitional contradiction as well as a problem in the Divine essence, He would never develop Christianity to save us all for it is not necessary as per (1). **Proof of (2)** (Minor Side Note:) I tried to put this into a single paragraph form though I could write 20 pages on this to properly show you how it would work. For anyone interested, watch [this video](https://www.youtube.com/watch?v=UTEkuo4i3N0) to perhaps give you a better idea as to what this is about if you don't understand it. This is not essential to the argument so much as I am more concerned about (1), so I'd rather have that be the focus in the refutation than this, which I am confident and able to defend. But a super rough broken-down sketch would go as follows: Since in the context of the Necessarily Existing Being, essence is identical to His existence, God cannot not exist. It also follows that since He is not contingent/dependent (as an existent), He cannot contain any composition and thus is Absolutely Divinely Simple (see different approaches as to how different Christian scholars tried to square the Trinity with this. As a side tip: avoid any Christian scholar who tries to do nonsense like deny that there is an existent which is Necessary). Also God since He is perfect and immaterial and thus not bound to time of physics, cannot undergo change. Since making arbitrary and unnecessary choice would either lead to internal contingency as He would have the ability to make a selection from choices or it would lead to external contingency (which would require essentially saying that things just popped up into existence, and would violate the principle of sufficient reason), neither of these options are possible. Hence it is not possible that God's choice is arbitrary in His divine essence. Any action which could possibly be arbitrary or unnecessary is not possible and can be understood as an irrational anthropomorphic projection on the behalf of the person. Moreover God's actions can never be arbitrary since the Divine essence cannot undergo change. Therefore, God would never arbitrarily or unnecessarily create Christianity as a means of having people save themselves if Christianity is unnecessary since people can be saved through other means. **Conclusion 2**: If it's possible to be saved without belief in Jesus as per (1) and God does not arbitrarily do anything unless it would be an impossibility (logical impossibility, contradiction) for it to be otherwise as per (2), then it follows that Christianity is an impossibility. I hope that everything is clear from this. I would really appreciate a thorough refutation. If I made any spelling mistakes, etc. also let me know because I just wanted to write this up quickly from my rough notes and then have it tested against different people to see what objections can be made.