Jews and Gentiles came from very different backgrounds. Bringing them together as one was a challenge. The situation was made more difficult by a faction of Jewish Christians that demanded, in effect, that Gentiles become Jewish.
Some men came down from Judea and were teaching the brothers, “Unless you are circumcised according to the custom of Moses, you cannot be saved.” … Some believers who belonged to the party of the Pharisees rose up and said, “It is necessary to circumcise them and to order them to keep the Law of Moses” (Acts 15:1, 5).
This challenge was addressed by the apostles and the elders in Jerusalem (Acts 15). In a sense, the question was, “What is the one faith that should be preached? Should it include the Law of Moses?” In answer, Peter recounted how God first used him to share the Gospel with Cornelius and his family (Acts 10). Peter concluded,
[God] made no distinction between us [Jews] and them [Gentiles], having cleansed their hearts by faith. … We believe that we will be saved through the grace of the Lord Jesus, just as they will (Acts 15:9, 11).
We believe we will be saved through the Lord’s grace.
There is no distinction! God saves by grace, not by obedience to the Law of Moses! God works through faith to cleanse hearts! If you are familiar with Ephesians, you recognize these truths as central to its message.