Under both covenants, circumcision is real. In the first Covenant, it is a natural or fleshly circumcision, involving only the physical body. Under the New Covenant, circumcision changes the innermost part of our being. 

(1) Under the old Covenant real blood was shed and a cut made in the skin. A portion of a man’s body, a layer of skin, was cut from him. God required the removal of something with which he was born. This was to show the intervention of God upon his life. Since he had met God and entered into covenant relationship, he was not the same. 

(2) Under the New Covenant something spiritual is removed from us, but it is something equally real. Our old “fleshly” nature, called “the old man” or “the body of sin” is cut away from us when we are buried with Christ in baptism. Something is really buried. The enmity between us and God comes to an end. 

In Him also you were circumcised with a circumcision not made with hands, but in a [spiritual] circumcision [performed by] Christ by stripping off the body of the flesh [the whole corrupt, carnal nature with its passions and lusts]. [Thus you were circumcised when] you were buried with Him in [your] baptism, in which you were also raised with Him [to a new life] through [your] faith in the working of God [as displayed] when He raised Him up from the dead (Col.2:11, 12, AMP)