Acts 15 reports controversy over circumcision. This controversy over fundamental Jewish practice arose again and again in the New Testament.

But some men came down from Judea and were teaching the brethren, “Unless you are circumcised according to the custom of Moses, you cannot be saved.”                                                                                  (Acts 15:1)

The dispute was whether Gentiles who had been baptized into Jesus had to be circumcised. The outcome in Acts 15 was that they did not, but it was still assumed that Jewish Christians would practice circumcision. Obviously there is the strongest Old Testament support for Jews, even when converted to Christ, continuing circumcision. For a time, to win over the Jews, Paul was willing to meet Jewish sensitivity.

Paul wanted Timothy to accompany him; and he took him and circumcised him because of the Jews that were in those places, for they all knew that his father was a Greek.                                                              (Acts 16:3)

But the logic of the New Covenant was that ritual practices of this sort were no longer relevant either for Jews or Gentiles:

Now I, Paul, say to you that if you receive circumcision, Christ will be of no advantage to you.  I testify again to every man who receives circumcision that he is bound to keep the whole law. You are severed from Christ, you who would be justified by the law;  you have fallen away from grace. For through the Spirit, by faith, we wait for the hope of righteousness. For in Christ Jesus neither circumcision nor uncircumcision is of any avail, but faith working through love.                                              (Galatians 5:2-6)

For neither circumcision counts for anything, nor uncircumcision, but a new creation.  Peace and mercy be upon all who walk by this rule, upon the Israel of God.                                                               (Galatians 6:15-16)

For he is not a real Jew who is one outwardly, nor is true circumcision something external and physical.  He is a Jew who is one inwardly, and real circumcision is a matter of the heart, spiritual and not literal. His praise is not from men but from God.                                       (Romans 2:28-29)

Paul, therefore, applied to the practice of circumcision the teaching of Jesus that true worship is in spirit and truth.  The fact that Paul, under the guidance and inspiration of God, could declare redundant under the New Covenant such a fundamental Old Testament practice as circumcision, should set for us the general principle that Christian worship is a matter of the spirit and the heart, not a matter of physical acts.