“And he received the sign of circumcision, a seal of the righteousness of the faith which he had while still uncircumcised, that he might be the father of all those who believe, though they are uncircumcised, that righteousness might be imputed to them also” (Romans 4:11).
Our text from Romans 4:11 highlights two important terms: a “sign” and a “seal.”
A “sign” functions as 
a marker that points, indicates, designates, or directs our attention to something else. Much like a guidepost or road sign that points the way to another destination, the covenant sign of circumcision was not an end in itself. Instead, that sign pointed to (or designated) something else. That “something else” was Abraham’s faith in God to deliver on His promises.
In its historical context, a “seal” referred to a stamp that incorporated a signet or private insignia as a means of security or proof of origin. Much like a contemporary seal that is used to validate an official document, ancient seals were also employed for authentication purposes in the Biblical era.
A seal typically comprised a small amount of softened wax that was affixed to the enclosure of a letter or official document. A signet ring or other distinguishing mark was then pressed into the soft wax to authenticate the enclosed information. This method of identification proved especially valuable for letters and other forms of correspondence, for it served to establish a document’s provenance and verify its authenticity.
In a similar manner, the act of circumcision pointed to the covenant (or agreement) that God established with Abraham….
“Then [the Lord] brought [Abraham] outside and said, ‘Look now toward heaven, and count the stars if you are able to number them.’ And He said to him, ‘So shall your descendants be.’ And he believed in the Lord, and He accounted it to him for righteousness” (Genesis 15:5-6).
This interaction functioned as the “seal” that verified and affirmed Abraham’s faith long before he received the ritual sign of circumcision. In other words, circumcision did not confer righteousness upon Abraham or his descendants. Instead, that act pointed to Abraham’s right standing with God in view of the faith he already possessed. Paul the Apostle alluded to this concept earlier in chapter four when he said, “For what does the Scripture say? “Abraham believed God, and it was accounted to him for righteousness” (Romans 4:3).
But what did these things mean for the original audience for the book of Romans, and what do they mean for contemporary readers of this letter? Paul will unpack the answer to those questions with a straightforward response in the following verse.