So, let me ask you a question. To become a Christian, does one need to become a "Baptist?" What about "Catholic?" "Methodist?" or "Pentecostal?"
The early church struggled with a similar issue, "Should a new Christian who was a gentile become Jewish?" More to the point, "Should new gentile Christian be circumcised?" Remember that circumcision was a sign for the people of Israel that they, through Abraham, had entered into a covenant with the Lord (Gen 17: 1-14). If this was so, shouldn't now new Christians, who were not Jews by birth, be circumcised as a sign of that old covenant with Lord?
Romans 2:25- 29 begins an idea of what true circumcision really is in the eyes of God. It seems that God does not consider a man a Jew if he is physically circumcised but does not practice the Law. Furthermore, God says that a Gentile who was not outwardly circumcised but keeps the Law will be regarded circumcised! Is that blasphemy? To the Jews it seemed so but God is more concerned about a circumcision which is of the heart, by the Spirit, and not by the mere letter of the Law. (Romans 2:29).
So, was the Lord saying for the Gentiles not to be circumcised? Galatians 5 gives that answer. If one receives circumcision then Christ will be no benefit to them (Gal 5:2) For in Christ Jesus neither circumcision nor uncircumcision means anything, but faith working through love (Gal 5:6). It goes even further to the point of being vulgar later in verse 12, "I wish that those who are troubling you would mutilate themselves!"
Why would God's word be so violently opposed to the very thing God commanded Abraham and all his children to do? Because Christ came to free us. From what? The law of sin and death. Now, how can one know what is sinful in the eye of the Lord? That's what the Law was for the reveal sin so that a sinner might turn to the Lord for forgiveness and God's grace might abound (Gal 3: 15-25, Romans 5:20-21).
So what does circumcision have to do with finding whom identity in a "religious" group today? I would be so bold to say that it is the very same thing. If a man's faith is based on anything other than the miraculous work power of Jesus in His death, resurrection, and ascension, then what is it good for? Nothing ... worse that nothing ... it will receive God's wrath and the second death (Rev 20:14-15)! It is by Christ and Christ alone that a man can be saved.
Again, let me ask does one need to be "Baptist" to be saved? "Catholic?" "Methodist?" "Pentecostal?" If the answer is no then let me ask you very plainly. Does one need to be a member of any religious group to be saved? I'm sure you already know the answer; none ... except the universal body of Christ, which knows no political boundaries, no racial differences, no economic strata, and no cultural distinctions.
Does that mean we don't have to join a local gathering of a group of believers, which is sometimes called the "local church?" No, because Hebrews 10:23-25 tells us that the local church is one of the ways God uses to help us "hold fast the confession of our hope without wavering" and be encouraged to love others and do good works. So, it is for our benefit to attend a local church. However, our identity must be found only in Christ and the finished work that He has done so many years ago.