Acts 15
The background to this text was a dispute that threatened the unity of the early church. The first christians did not initially abandon Judaism to form a new religion. The separation was gradual as they were thrown out of the synagogues for preaching Jesus as the Jewish Messiah.
As the good news spread to gentiles a disagreement arose about whether these new christians should be required to get circumcised and keep the Law. A council was arranged at Jerusalem to settle the matter. Their decision appealed to a provision of the Law that satisfied both parties. In ancient Israel it was not necessary for a foreigner to adopt Judaism by becoming a proselyte. They could live at peace with their Jewish hosts as long as they observed a few necessary laws.
Leviticus mentions the need for foreigners to adhere to a few basic requirements of the Law such as avoiding idolatry, fornication and the misuse of blood. This is the formula adopted by the Jerusalem council. They decide not to burden gentile christians beyond the need to observe these "necessary things".
This then was not a new set of laws invented for christians, it was an instruction to adhere to those minimum requirements of the Mosaic Law that were incumbent on alien residents in Israel, "For in every city, for generations past, Moses has had those who proclaim him, for he has been read aloud every sabbath in the synagogues.” - Acts.15:21
The instruction to abstain from blood is the same law that required a foreigner in Israel to bleed an animal killed for food but permitted him to eat an unbled animal found already dead.