Answer from Paul (Romans):
"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 (pneuma).”
The Apostles declares in Romans 2:25-29: “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 (pneuma).”
Salvation is not about one's natural state, birthplace, birthday or parents. It is not about the physical act of circumcision - that is meaningless. It is about spiritual birth. It is about becoming a new creature through an inward work of circumcising the heart. What this is saying is that one's Jewishness (circumcision) means nothing if one isn’t saved, if one is saved then his Jewish upbringing has benefited him by somewhere bringing him into contact with the truth (Christ). I don't in any way believe this is talking about the physical act of circumcision but rather one's Jewishness. Jews were known as "the circumcision." This was a title that really denoted "Jew." We know it cannot be the act of circumcision as it avails nothing.
There is a difference between the Ten Commandments, written by God on stone and carried inside the Ark of the Covenant, and the Mosaic Law, scribed by Moses on parchment and carried outside of the Ark.
Circumcision is not in the Ten Commandments.