Actually, we know quite a bit about the significant events in Jesus life. They were so extraordinary and witnessed by so many thousands of people that a number of contemporary historians wrote about them. In particular, Josephus, who was a Pharisee, and Tacitus, who was a Roman historian, both acknowledged many of the extraordinary things that happened in Jesus’s life. They both wanted to deny what people claimed to have seen, but they could not because there were literally thousands of witnesses.
In the case of Josephus, he was looking for a way to debunk what he perceived, as the cult of personality surrounding Jesus. The early Christians were a threat to the established Jewish order. He grudgingly accepted the fact of the resurrection and some of the miracles because he could not get around it. He ultimately argued that Jesus was in league with the devil, and that’s why he was able to do miraculous things. In the case of Tacitus, Israel had been a troublesome outpost of the Roman Empire for a long time. Shortly after his death, a major Maccabean revolt occurred resulting in a years long siege of Masada. The last thing Tacitus wanted to do was to acknowledge that maybe Jesus was more divine than the Roman emperor. That undermined his authority. The problem was he couldn’t get around it. He was a conscientious historian, who tried to relate the actual facts, not his opinions.
These are just two examples. Something quite extraordinary happened two thousand years ago. There are many others who wrote about the events because they were earthshaking at the time. If the point of your comment was, we don’t know a lot about the specifics of Jesus’s day-to-day life before his ministry, you are correct. We don’t. But we know quite a bit about his life when he began his ministry.
Part of the point of my comment was that there were many sacred books written in the first several hundred years of the Common Era and even earlier and by a variety of different faith traditions. There are a lot of inaccuracies and superstition and cultural biases in the Bible, particularly in the Old Testament. There are also a lot of passages that are misunderstood because modern people have no familiarity with the literary devices utilized by ancient authors to make a point. They frequently get it wrong. But there are some undeniable truths and life affirming things as well, which is why Christianity has been so durable.
I push back against the fundamentalists who suggest that it is the only truth and think that every word is inerrant, dictated directly by God to man. It isn’t. It was written by many different authors over thousands of years, who were far more ignorant than people are today. They tried their best to explain unusual events and often got it wrong. They also had a rather paternalistic view towards society. The fundamentalist version of Christianity is one of self righteous judgmentalism, where they have recast God in their own image, and have no understanding of the truly divine. They use the Bible as a supposedly unassailable absolute authority to control and condemn those who do not fit their narrative and view of reality. They use selective snippets to justify their position, but ignore those things which do not conform to their intolerant views.
The authentic message is about love, acceptance, and forgiveness. I think many people over the centuries have had divine encounters and many different faith traditions have things to offer to help us fully understand the nature of God better.
The gnostic gospels were written by the Coptic Christians, who were a bit of a cult and did not last long. But even they have something to add to the narrative. No one faith tradition has an exclusive claim to the truth.