Before christianity .....hence ( before christ). God made a promise to Abraham to make his family line, the one that would give birth to the savoir Jesus Christ.
This started the Jewish religion ( as accounted by Moses). They had very detailed and burdensome laws to live by though. This was the price for them to pay to be Gods chosen people.
This was called the Mosaic law. Not just 10 comandments, but hundreds. The local jewish scholars were called Pharisee's and Saducee's. They added huge amounts of more details that were not required.
Hence when Jesus ( Gods son ) finally got here. The mosaic law was really messed up and Jesus taught that he was the new law. Matt 5:17. It was shocking to the jews that Jesus was healing people on sabbath days. He was eating with prostitutes and lepers. The Jews hated him, they were pompous and self-rightous.
True christianity was born, but less tha 100yrs after he died, pagan beliefs started entering the church again. But the truth is still out there.