The physical act of circumcision was the physical sign of the Abrahamic Covenant between God and Abraham. Abraham is considered the first Jew partially because he is the first known human to be circumcised. All Jewish male descendants of Abraham were to also be circumcised. Today, in many Jewish denominations, including orthodox, conservative, some reform and some messianic, many Jewish males are still circumcised on the eighth day.
This is My covenant, which you shall keep, between Me and you and your descendants after you: every male among you shall be circumcised. And you shall be circumcised in the flesh of your foreskin; and it shall be the sign of the covenant between Me and you (Genesis 17:10-11).
And on the eighth day the flesh of his foreskin shall be circumcised (Lev. 12:3). Jesus, being born a Jew, eight days after he was born, was circumcised. And at the end of eight days, when he was circumcised, he was called Jesus, the name given by the angel before he was conceived in the womb (Luke 2:21). This was part of His fulfillment of the Torah.
This topic comes up often in the New Testament. While everyone understood the commandment of the physical circumcision, not everyone understood the spiritual circumcision that would take place when one sincerely wanted to do as the Lord commanded.
The Lord indicates that physical circumcision is insufficient to put an individual in a right relationship with him. True circumcision must be an act of the heart.(1)
He first indicated it through Jeremiah, "Circumcise yourselves to the Lord; remove the foreskin of your hearts, O men of Judah and inhabitants of Jerusalem; lest my wrath go forth like fire, and burn with none to quench it, because of the evil of your deeds” (Jer. 4:4).
The Lord then re-affirmed this again through Paul (who was also circumcised on the eight day-Phil. 3:5) in the Book of Romans. Paul, writing about what a true Jew really was wrote, "For no one is a Jew who is merely one outwardly, nor is circumcision outward and physical. But a Jew is one inwardly, and circumcision is a matter of the heart, by the Spirit, not by the letter. His praise is not from man but from God" (Romans 2:28-29). Paul sees circumcision on more of a spiritual level than a physical level.
Believers in Jesus are "circumcised" spiritually because of Christ Himself. "In him also you were circumcised with a circumcision made without hands, by putting off the body of the flesh, by the circumcision of Christ"... (Colossians 2:11).
Both Jewish and Gentile believers in Jesus as Messiah are treated the same concerning circumcision because the circumcision comes from God spiritually "For in Christ Jesus neither circumcision nor uncircumcision counts for anything, but only faith working through love" (Galatian's 5:6).
The Galatian's 5:6 verse helps to shed light on the teaching of Jesus. Concerning the written law (remember circumcision was the first law a Jewish person was introduced to) Jesus wrote:
You shall love the Lord your God with all your heart, and with all your soul, and with all your mind. This is the great and foremost commandment. The second is like it, You shall love your neighbor as yourself. On these commandments depend the whole Law and the Prophets” (Matthew 22:37-40).
Behold, the days are coming, declares the Lord, when I will punish all those who are circumcised merely in the flesh— (Jer. 9:25).
Miscellaneous information goes here.
1). Newman, Barclay Moon ; Stine, Philip C.: A Handbook on Jeremiah. New York : United Bible Societies, 2003 (UBS Handbook Series), S. 120