Only you are talking about this. The rest of us are wondering why you insist on talking about this.
Mainly because it’s not an interesting question.
- Did Christians exist in history? Yes. Lots of them. Nobody disputes that.
- What did they believe? Well, actually they believed all sorts of things, and occasionally went to war with each other over these differences.
- Was what they believed true? Was what which Christians believed true? Whatever aspect you’re talking about, there was a historical group of people who considered themselves Christian who believed something else, up to and including the divinity of Christ and his resurrection. Aspects of the story are undeniably true. Aspects of the story are plausible in context. Aspects of the story are based on known unreliable narratives. And aspects of the story are literally miracles and are perforce articles of faith.
That people believed it was a historical fact is a trivial and boring statement. Whether the belief is justified is the basis of two thousand years of theology and warfare. It’s also not going to be decided here.