The apostle Paul was quite clear that circumcision is not a requirement for salvation.  He told the brethren in Corinth to remain circumcised if circumcised or uncircumcised if uncircumcised.

1Co 7:18  Was anyone called while circumcised? Let him not become uncircumcised. Was anyone called while uncircumcised? Let him not be circumcised.

Paul’s message was don’t change your state of circumcision that you had when God called you, (that is when God opened your eyes to the truth).  He then went on to say that being circumcised or uncircumcised is not important, but keeping the commandments of God is important.

1Co 7:19  Circumcision is nothing and uncircumcision is nothing, but keeping the commandments of God is what matters.

Paul wrote something similar to the brethren in Galatia.  Being circumcised or uncircumcised doesn’t matter, but rather faith working through love.

Gal 5:6  For in Christ Jesus neither circumcision nor uncircumcision avails anything, but faith working through love.

That should be the end of the matter.  However, there are some Christians who, although acknowledging that circumcision is not required for salvation, argue that circumcision has physical benefit and therefore encourage it. 

A quick internet search will find various scientific studies which indicate circumcised men are less likely to be infected with sexually transmitted diseases than uncircumcised men.  So, yes, circumcision could provide a health benefit for promiscuous men, but there is no health benefit of circumcision for Christian men (who don’t have sex if single or who only have sex with their wife if married).

It should be noted that circumcision can benefit men who have particular rare medical conditions.

We should also remember that God said of His creation that it was “very good”.

Gen 1:31  Then God saw everything that He had made, and indeed it was very good. So the evening and the morning were the sixth day.

Thus, since Adam was created uncircumcised, his uncircumcision was also very good.  Therefore we can conclude that in general uncircumcision is very good.

Conclusion

Circumcision is not a requirement for salvation. In general uncircumcision is very good.