1 Corinthians 7:19

Circumcision is nothing, and uncircumcision is nothing, but the keeping of the commandments of God (KJV)

Then: Oops. The Jews in Corinth just hit a conundrom, but Paul ignores it. Keeping the commandments is a top priority for Jews and new followers of Christ alike. Paul's focus is on the end game, Christ as the fulfillment of the Law. From days of the Old Covenant, circumcision was required. In the days of the New Covenant, the sign of faithfulness and commitment signified by circumcision is no longer important. Accepting Christ as the Son, an integral, inseparable part of God supreme and the one way to salvation has top priority. After that, all other aspects of obedience fall into place. Paul skips the explanation (although discussing it in Romans) and keeps pursuing answers to the Corinthians' questions.

Now: If you find the KJV hard to read, substitute "what's really important is" for the word "but." That's the essence of N. T. Wright's translation (p. 84). During World War II, Hitler used circumcision to identify Jews. He was astounded to learn that many Western Christians were circumcised too. Currently, there is a push to completely eliminate the practice. The mantra is that the procedure does cause pain to seven-day old infants and is not effective in preventing diseases. Some may suspect an underlying agenda of devaluing Christian beliefs. That can not happen if today's believers lock in to Paul's teachings: Love Christ, know Christ, serve Christ, teach Christ. That's the alpha and omega of being a Christian.

1 Corinthians 7:18

Is any man called being circumcised? let him not become uncircumcised. Is any called in uncircumcision? let him not be circumcised (KJV)

Then: Paul never leaves his hearers without examples. The original question could have come from the Corinthians, or it could have come from other churches. Along with having both a physical and spiritual meaning, the query fits into his current teaching point and principle of "Stay where you are when called by the Lord." Notice that "circumcision" is another way for Paul to say "Jewish," and "uncircumcised" is a way to refer to "Gentiles" or "pagans." There is no reason to become circumcised when the people the Corinthians would influence about Christ's lordship are those who are already associates. Most likely they were not circumcised. Vice-versa, if a Corinthian was a Jew, the people whom they would influence most are other Jews. The spiritual meaning is the Corinthians' daily task of telling others about Christ.

Now: Today's Christians use the same principle, inasmuch as it is possible. If they are able to speak with past friends individually without being pulled back into a former life - such as the drug culture or gang mentality, then they are free to keep close associations. However, if the influence of the other is greater than the believer's strength of purpose, close associations are not advisable. Anyone looking at Paul's biography notices the multi-year gap between his conversion and his ministry. Before turning to a life of daily service to the Lord Paul took time to withdraw and re-orient his world view by studying Christ. Believers need both Paul's teaching and example in order to be effective followers.