“Some men came down from Judea and began teaching the brethren, “Unless you are circumcised according to the custom of Moses, you cannot be saved.” And when Paul and Barnabas had great dissension and debate with them, the brethren determined that Paul and Barnabas and some others of them should go up to Jerusalem to the apostles and elders concerning this issue.
Therefore, being sent on their way by the church, they were passing through both Phoenicia and Samaria, describing in detail the conversion of the Gentiles, and were bringing great joy to all the brethren. When they arrived at Jerusalem, they were received by the church and the apostles and the elders, and they reported all that God had done with them.
But some of the sect of the Pharisees who had believed stood up, saying, “It is necessary to circumcise them and to direct them to observe the Law of Moses.”
The apostles and the elders came together to look into this matter.
After there had been much debate, Peter stood up and said to them, “Brethren, you know that in the early days God made a choice among you, that by my mouth the Gentiles would hear the word of the gospel and believe.
“And God, who knows the heart, testified to them giving them the Holy Spirit, just as He also did to us; and He made no distinction between us and them, cleansing their hearts by faith.
“Now therefore why do you put God to the test by placing upon the neck of the disciples a yoke which neither our fathers nor we have been able to bear?
“But we believe that we are saved through the grace of the Lord Jesus, in the same way as they also are.” Acts 15:1-11. (Emphasis added.)
Now, here is Galatians 3:1-6. Paul likewise here opposed those who were trying to teaching that circumcision and the works of the Law were necessary for perfection. Note how Paul here likewise focuses on receiving the Holy Spirit, hearing with faith, and salvation through grace as compared to salvation through the Law.
“You foolish Galatians, who has bewitched you, before whose eyes Jesus Christ was publicly portrayed as crucified?
This is the only thing I want to find out from you: did you receive the Spirit by the works of the Law, or by hearing with faith?
Are you so foolish? Having begun by the Spirit, are you now being perfected by the flesh?
Did you suffer so many things in vain–if indeed it was in vain?
So then, does He who provides you with the Spirit and works miracles among you, do it by the works of the Law, or by hearing with faith?
Even so Abraham BELIEVED GOD, AND IT WAS RECKONED TO HIM AS RIGHTEOUSNESS.” Galatians 3:1-6. (Emphasis added.)
Reformed Doctrine Daily Devotions 