What the Bible says about
Circumcision

"Circumcise therefore the foreskin of your heart, and be no more stiffnecked."
Deuteronomy 10:16.

"And the LORD thy God will circumcise thine heart, and the heart of thy seed, to love the LORD thy God with all thine heart, and with all thy soul, that thou mayest live."
Deuteronomy 30:6.

"Circumcise yourselves to the LORD, and take away the foreskins of your heart, ye men of Judah and inhabitants of Jerusalem: lest my fury come forth like fire, and burn that none can quench it, because of the evil of your doings."
Jeremiah 4:4.

"Behold, the days come, saith the LORD, that I will punish all them which are circumcised with the uncircumcised; Egypt, and Judah, and Edom, and the children of Ammon, and Moab, and all that are in the utmost corners, that dwell in the wilderness: for all these nations are uncircumcised, and all the house of Israel are uncircumcised in the heart."
Jermiah 9:25-26.

"And certain men which came down from Judaea taught the brethren, and said, Except ye be circumcised after the manner of Moses, ye cannot be saved."
Acts 15:1 (read the rest of the chapter for the "whole" story).

"And the day following Paul went in with us unto James; and all the elders were present. And when he had saluted them, he declared particularly what things God had wrought among the Gentiles by his ministry. And when they heard it, they glorified the Lord, and said unto him, Thou seest, brother, how many thousands of Jews there are which believe; and they are all zealous of the law: And they are informed of thee, that thou teachest all the Jews which are among the Gentiles to forsake Moses, saying that they ought not to circumcise their children, neither to walk after the customs."
Acts 21:18-21.

"For circumcision verily profiteth, if thou keep the law: but if thou be a breaker of the law, thy circumcision is made uncircumcision. Therefore if the uncircumcision keep the righteousness of the law, shall not his uncircumcision be counted for circumcision? And shall not uncircumcision which is by nature, if it fulfil the law, judge thee, who by the letter and circumcision dost transgress the law? For he is not a Jew, which is one outwardly; neither is that circumcision, which is outward in the flesh: But he is a Jew, which is one inwardly; and circumcision is that of the heart, in the spirit, and not in the letter; whose praise is not of men, but of God."
Romans 2:25-29.

"But as God hath distributed to every man, as the Lord hath called every one, so let him walk.  And so ordain I in all churches. Is any man called being circumcised? let him not become uncircumcised.  Is any called in uncircumcision? let him not be circumcised. Circumcision is nothing, and uncircumcision is nothing, but the keeping of the commandments of God. Let every man abide in the same calling wherein he was called.
1 Corinthians 7:17-20.

"Stand fast therefore in the liberty wherewith Christ hath made us free, and be not entangled again with the yoke of bondage. Behold, I Paul say unto you, that if ye be circumcised, Christ shall profit you nothing. For I testify again to every man that is circumcised, that he is a debtor to do the whole law. Christ is become of no effect unto you, whosoever of you are justified by the law; ye are fallen from grace. For we through the Spirit wait for the hope of righteousness by faith. For in Jesus Christ neither circumcision availeth any thing, nor uncircumcision; but faith which worketh by love."
Galations 5:1-6.

"As many as desire to make a fair shew in the flesh, they constrain you to be circumcised; only lest they should suffer persecution for the cross of Christ. For neither they themselves who are circumcised keep the law; but desire to have you circumcised, that they may glory in your flesh."
Galations 6:12-13.

"In whom also ye are circumcised with the circumcision made without hands, in putting off the body of the sins of the flesh by the circumcision of Christ:"
Colossians 2:11.

"But now ye also put off all these; anger, wrath, malice, blasphemy, filthy communication out of your mouth. Lie not one to another, seeing that ye have put off the old man with his deeds; And have put on the new man, which is renewed in knowledge after the image of him that created him: Where there is neither Greek nor Jew, circumcision nor uncircumcision, Barbarian, Scythian, bond nor free: but Christ is all, and in all."
Colossians 3:8-11.

"For there are many unruly and vain talkers and deceivers, specially they of the circumcision:"
Titus 1:10.