In baptism we become members of the Church
There is no doubt that baptism was symbolised by circumcision in the Old Testament. The Apostle St. Paul says about the Lord Jesus: "In Him you were also circumcised with the circumcision made without hands, by putting off the body of the sins of the flesh, by the circumcision of Christ, buried with Him in baptism, in which you also were raised with Him through faith in the working of God, who raised Him from the dead" (Col.2: 11,12).
It is known that in circumcision a part of the body is cut off and it dies. This refers to the complete death in baptism.