Jesus was a genuine historical person. The Israelites were waiting for the promised Jewish saviour who would free Israel from Roman rule. They thought Jesus would do that and wanted to make him king. That is why he was tried for sedition. The Romans killed hundreds of thousands of Christians, usually torturing them to death.
As the roman empire faded, it looked around for a religion to adopt that ticked all the right boxes. The Jewish religion with so many martyrs was ideal. Rome adopted the Jewish faith along with Christ and Christianity was established. The Holy Roman Empire was established. Suddenly, anyone who did not convert to Christianity was pagan.
When secular Rome lost it power, the Holy Roman Empire survived as planned. The Vatican survives to this day as an untouchable, un-taxable power base. It is all a trick, because with Christ Jesus and his apostles dead, all power and glory went to the Holy Roman Empire.
Oh I forget about God - so did the Romans!