Feed your Faith and your doubts will starve to death, for we walk by faith, not by sight. For in Christ Jesus neither circumcision nor uncircumcision avails anything, but faith working through love. One of the rituals of the Jewish religion is circumcision, an act which the Gentile believers rejected. Paul is talking in this passage about the religious significance of circumcision. In Christ Jesus religion means nothing.
Religion is made up of regulations, restrictions, and ritual.
None of those things count for God. Perhaps this will surprise some people who go through the ritual every Sunday, who adhere to the restrictions, who straighten up their lives in line with the regulations. Christianity is the way of a Father with His children. It is not a religion. Christianity works when faith is exercised by love.