Albert Barnes Commentary Romans 4:11

"and he received the sign of circumcision, a seal of the righteousness of the faith which he had while he was in uncircumcision; that he might be the father of all them that believe, though they be in uncircumcision, that righteousness might be reckoned unto them;" — Romans 4:11 (ASV)

And he received the sign, etc. A sign is that by which anything is shown or represented. And circumcision thus showed that there was a covenant between Abraham and God (Genesis 17:1–10). It became the public mark or token of the relation which he sustained to God.

A seal. (See the notes on John 3:33).

A seal is that mark of wax or other substance, which is attached to an instrument of writing, such as a deed, etc., to confirm or ratify it, or to make it binding. Sometimes instruments were sealed, or made authentic by stamping on them some word, letter, or device, which had been engraved on silver or on precious stones. The seal or stamp was often worn as an ornament on the finger (Esther 8:8; Genesis 41:42; Genesis 38:18; Exodus 28:11,36,39).

To affix the seal, whether of wax or otherwise, was to confirm a contract or engagement. In allusion to this, circumcision is called a seal of the covenant which God had made with Abraham. That is, God appointed this as a public attestation to the fact that he had previously approved of Abraham and had made important promises to him.

He believed (Genesis 15:6), and the faith which he had yet being circumcised was accepted, or he was justified; he was admitted to the favor of God and favored with clear and remarkable promises (Genesis 15:18–21; Genesis 17:1–9) before he was circumcised. Circumcision, therefore, could have contributed neither to his justification nor to the promise made to him by God.

That he might be the father, etc. All this was done so that Abraham might be held up as an example, or a model, of the very doctrine which the apostle was defending. The word father here is used evidently in a spiritual sense, denoting that he was the ancestor of all true believers and that he was their model and example. They are regarded as his children because they possess his spirit, are justified in the same way, and are imitators of his example. (See the notes on Matthew 1:1).

In this sense, the expression occurs in Luke 19:9; John 8:33; Galatians 3:7, 29.

Though they be not circumcised. This was stated in opposition to the opinion of the Jews that all ought to be circumcised. As the apostle had shown that Abraham enjoyed the favor of God before he was circumcised, that is, without circumcision, so it also followed that others could be accepted on the same principle. This instance settles the point, and there is nothing a Jew can reply to this.

That righteousness, etc. That is, in the same way, by faith without works, so that they might be accepted and treated as righteous.