I'm not "ignoring" your point, but disputing its correctness. You can only trace what you have documented in some way or another. But it's not necessary that

I'm not "ignoring" your point, but disputing its correctness. You can only trace what you have documented in some way or another. But it's not necessary that it be written by friendly sources. For example, you can learn that there was a group teaching that circumcision was required for Christians because some of Paul's writings criticize that group. That doesn't tell us that they were wrong and Paul was right, or even that Paul's characterization of them was totally accurate, only that Paul thought them noteworthy enough to criticize. What we know of early Christian documents is that they preserved not merely their own positive teachings, but criticisms of other groups. The writings we still have involve a fair bit of back-and-forth. They involve what might be called either "criticism" or "nuancing" of other parts of the same collection of writing. They involve criticism of teachings of other groups. My contention is that they, either directly or indirectly, preserved every truly-early variant of Christianity that had enough followers for anyone to care -- that, in essence, there isn't a big enough gap in history for a group like the gnostics to have existed and been significant prior to around the mid second century. Because there's no criticism of those ideas, and for a group that loves to criticize, that would be way out of character. And the documents are well-enough preserved to have not lost that. It's not, as some suppose, that there's a sketchy chain of preservation that we can't follow, and out the far end many centuries later comes a document we can't trace; instead, there's a broad spread of preservation by a bunch of different Christian communities on three different continents, who spoke different languages, and we can trace what sort of changes happened over time from different communities. We don't have to suppose a chain of accuracy-destroying alterations; we can establish fairly high certainty of most of the New Testament at least near the end of the first or start of the second century. Which is different from saying "proven eyewitness accounts" (though there are some things that point toward the accounts being written by people familiar with 1st-century Jewish culture in Palestine; one of the reasons I keep bringing up the names used in the canonical gospels is that they don't match Jewish diaspora names, but instead Palestine-region Jewish names, from the first century.) There are entire scholarly journals about this stuff. I don't mean "Christians convincing themselves"; there's a good mix of Christian and non-Christian scholars who study Biblical manuscripts and Biblical archaeology and so forth, and there's fairly broad agreement about the various sects that existed in the first couple of centuries. There's disagreement over who was "right", of course, but not particularly over which groups existed or were significant.