circumcisionpicture source: lstcccme.

In the Bible, circumcision was given as a commandment to Abraham:

"And God said to Abraham: “As for you, you shall keep My covenant, you and your descendants after you throughout their generations. This is My covenant which you shall keep, between Me and you and your descendants after you: Every male child among you shall be circumcised; and you shall be circumcised in the flesh of your foreskins, and it shall be a sign of the covenant between Me and you. He who is eight days old among you shall be circumcised, every male child in your generations, he who is born in your house or bought with money from any foreigner who is not your descendant. He who is born in your house and he who is bought with your money must be circumcised, and My covenant shall be in your flesh for an everlasting covenant. And the uncircumcised male child, who is not circumcised in the flesh of his foreskin, that person shall be cut off from his people; he has broken My covenant.”
 - Genesis 17:9-14 (NKJV)

Notice that the text consistently teaches that the descendants of Abraham, his children, his servants and the descendants of his servants need to be circumcised. This is the sign of the covenant between God and Abraham.

For a person to be able to keep the Passover ritual of the Jewish religion, he also needs to be circumcised:

"And when a stranger dwells with you and wants to keep the Passover to the Lord, let all his males be circumcised, and then let him come near and keep it; and he shall be as a native of the land. For no uncircumcised person shall eat it. One law shall be for the native-born and for the stranger who dwells among you."
 - Exodus 12:48-49 (NKJV)

In John 7:21-23, Jesus gives a quick reference to the fact that Moses gave the commandment of circumcision to the Jews and that it is necessary for the Jews to receive circumcision, as a means of not breaking the Law of Moses. Notice that Jesus affirms that circumcision is an obligation to the Jewish people. He also stated that the commandment of circumcision already started from the Patriarchs (Isaac, Jacob,… it started with Abraham, as we have seen in Genesis 17):

"But you work on the Sabbath, too, when you obey Moses’ law of circumcision. (Actually, this tradition of circumcision began with the patriarchs, long before the law of Moses.) For if the correct time for circumcising your son falls on the Sabbath, you go ahead and do it so as not to break the law of Moses. So why should you be angry with me for healing a man on the Sabbath?"
 - John 7:22-23 (NLT)

Now there where certain Pharisees, who might have become Christians according to the text, who claim that the Gentiles who became Christians also need to receive circumcision, in the same manner in which the Gentiles who wanted to become Jews were obligated to be circumcised:

 'And certain men came down from Judea and taught the brethren, “Unless you are circumcised according to the custom of Moses, you cannot be saved.”'
 - Acts 15:1 (NKJV)
'But some of the sect of the Pharisees who believed rose up, saying, “It is necessary to circumcise them, and to command them to keep the law of Moses.”'
 - Acts 15:5 (NKJV)

In the next verse, we see that “the apostles and the elders came together to look into this matter” (NASB).

James’ conclusion of the matter is:

"I judge that we should not trouble those from among the Gentiles who are turning to God, but that we write to them to abstain from things polluted by idols, from sexual immorality, from things strangled, and from blood."
 - John 15:19b-20 (NKJV)

There is an agreement with what James just said (verse 22) and a letter is being send to the Christian brothers, repeating the same rules and regulations (verse 23-29). The term “brothers” is being used, in this letter, which shows that they were considered to be Christians (contrary to the ideas of those Pharisees, see verse 1). Furthermore, it is clearly stated that the Church did not form the idea that the Gentiles need to be circumcised to become saved Christians, to those Pharisees. They  rather worked from their own notions:

“We have heard that some who went out from us have troubled you with words, unsettling your souls, saying, “You must be circumcised and keep the law” —to whom we gave no such commandment—”
– Acts 15:24b (NKJV)

Paul becomes furious with those who afterwards preach the same troubling teaching, that circumcision is necessary for the Gentiles:

"For in Christ Jesus neither circumcision nor uncircumcision is of any avail, but faith working through love. You were running well; who hindered you from obeying the truth?  This persuasion is not from him who calls you. A little leaven leavens the whole lump. I have confidence in the Lord that you will take no other view than mine; and he who is troubling you will bear his judgment, whoever he is. But if I, brethren, still preach circumcision, why am I still persecuted? In that case the stumbling block of the cross has been removed. I wish those who unsettle you would mutilate themselves!"
- Galatians 5:6-12 (RSV)

The only rules the Gentiles are obliged to follow, are the following:

"Abstain from things offered to idols, from blood, from things strangled, and from sexual immorality."
 - Acts 15:29b (NKJV)

In acts 21:25, the same rules are repeated for the Gentiles and it is explicitly stated that the Gentile believers do not need to be circumcised.

In Galatians 2:7, we see that Paul “had been entrusted with the gospel to the uncircumcised, just as Peter had been entrusted with the gospel to the circumcised” (RSV). Peter was sent to the Jews which are under God’s law of circumcision. Paul was sent to the Gentiles which are not obliged by God to be circumcised.

"When they saw that the gospel for the uncircumcised had been committed to me, as the gospel for the circumcised was to Peter (for He who worked effectively in Peter for the apostleship to the circumcised also worked effectively in me toward the Gentiles),  and when James, Cephas, and John, who seemed to be pillars, perceived the grace that had been given to me, they gave me and Barnabas the right hand of fellowship, that we should go to the Gentiles and they to the circumcised."
 - Galatians 2:7b-9 (NKJV)

By means conclusion: the Bible makes clear that God never gave the command of circumcision to the Gentiles who want to become Christians. We can read in the Pentateuch that it was only given to Abraham through specific revelation, for him, his descendants, servants and Gentiles wanting to become Jews. The Bible never abolishes this rule for the Jews and never introduces it as a rule for Christian Gentiles. There is no need for some sort of dispensational theology concerning this matter.