Jesus was born into the tribe of Judah, one of the 12 tribes of Israel, in Judaea, then part of the Roman Empire. The Jews believed in one god, and that a ‘messiah’ would come, as prophesied, to save the world.
Jesus (one of many spiritual teachers of the time) and Emperor Augustus were both called ‘son of god’ and saviour of the world. The big difference was that Augustus was wealthy and the most powerful man in the Roman Empire. Jesus was a homeless vagrant.
Why did belief in Jesus as divine saviour endure?
The Romans treated the Jews terribly and expelled them from Judea. The Jews made Christianity open to all. A common language facilitated its spread.
Christianity favoured the poor, who have always outnumbered the rich. Eventually, the Roman Emperor Constantine supported it, becoming Christian himself and dynamically spreading the religion.