The Catechism of the Catholic Church, Second Edition says:
1150 Signs of the covenant. The Chosen People received from God distinctive signs and symbols that marked its liturgical life. These are no longer solely celebrations of cosmic cycles and social gestures, but signs of the covenant, symbols of God's mighty deeds for his people. Among these liturgical signs from the Old Covenant are circumcision, anointing and consecration of kings and priests, laying on of hands, sacrifices, and above all the Passover. The Church sees in these signs a prefiguring of the sacraments of the New Covenant.
527 Jesus circumcision, on the eighth day after his birth, is the sign of his incorporation into Abraham's descendents, into the people of the covenant. It is the sign of his submission to the law and his deputation to Israel's worship, in which he will participate throughout his life. This sign prefigures that "circumcision of Christ" which is Baptism.
Romans 4:11 denies that divine external rites are sacramental. They are a "sign and seal" of things already accomplished rather than things accomplished during the application of the external rite.
Rom. 4:11 And he received the sign of circumcision, a seal of the righteousness of the faith which
he had yet being uncircumcised: that he might be the father of all them that believe,
though they be not circumcised; that righteousness might be imputed unto them also:
Now simply place baptism in the place of circumcision in this context:
9 ¶ Cometh this blessedness then upon the
baptized only, or upon the
unbaptized also? for we say that faith was reckoned to Abraham for righteousness.
10 How was it then reckoned? when he was
baptized, or
unbaptized?
Not in baptism, but in unbaptism.
11 And he received the sign of baptism, a seal of the righteousness of the faith which
he had yet being unbaptized: that he might be the father of all them that believe,
though they be not baptized; that righteousness might be imputed unto them also:
12 And the father of baptism to them who are not of the baptized only, but who also walk in the steps of that faith of our father Abraham, which he had being yet unbaptized.
Abraham is THE EXAMPLE or PATTERN that Paul chooses to set forth for justification by faith in order to remove all boasting (Rom. 3:27; 4:1-2).
the Justification is defined in Romans 4:6-8 to include the "blessedness" of both remission of sins and imputed righteousness.
Abraham received this "blessedness" while still in uncircumcision not in circumcision. Hence, circumcision was not sacramental in character or nature as justification was not imparted, imputed, received during circumcision and the same is true with baptism.