It is the fatal error of Romanists and other Ritualists that signs and seals actually convey grace of themselves. Not so: only as faith is operative in the use of them are they means of blessing. Romans 4:11 helps us at this point: “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.” Unto Abraham, circumcision was both a sign and a seal: a sign that he had previously been justified, and a seal (pledge) that God would make good the promises which He had addressed to his faith. The rite, instead of conferring anything, only confirmed what Abraham already had. Unto Abraham, circumcision was the guarantee that the righteousness of faith which he had (before he was circumcised) should come upon or be imputed unto believing Gentiles. Thus as the rainbow was the confirmatory sign and seal of the covenant promises God had made to Noah, as circumcision was the sign and seal of the covenant promises God had made to Abraham, so the tree of life was the sign and seal of the covenant promises He had made to Adam. It was appointed by God as the pledge of His faithfulness, and as an earnest of the blessings which continued fidelity would secure. Let it be expressly pointed out that, in keeping with the distinctive character of this present antitypical dispensation—when the substance has replaced the shadows—though baptism and the Lord’s Supper are divinely appointed ordinances, yet they are not seals unto the Christian. The seal of “the new covenant” is the Holy Spirit Himself (see 2 Cor. 1:22; Eph. 1:13; 4:30)! The gift of the blessed Spirit is the earnest or guaranty of our future inheritance…
The next thing we would observe is that circumcision was “a seal of the righteousness of the faith which he had.” Again we would say, Let us be on our guard against adding to God’s Word, for nowhere does Scripture say that circumcision was a seal to anyone but to Abraham himself; and even in his case, so far was it from communicating any spiritual blessing, it simply confirmed what was already promised to him. As a seal from God, circumcision was a divine pledge or guaranty that from him should issue that seed which would bring blessing to all nations, and that, on the same terms as justifying righteousness had become his—by faith alone. It was not a seal of his faith, but of that righteousness which, in due time, was to be wrought out by the Messiah and Mediator. Circumcision was not a memorial of anything which had already been actualised, but an earnest of that which was yet future—namely, of that justifying righteousness which was to be brought in by Christ.
But did not God enjoin that all the males of Abraham’s household, and in those of his descendants, should also be circumcised? He did, and in that very fact we find definite confirmation of what has just been said above. What did circumcision seal to Abraham’s servants and slaves? Nothing. “Circumcision neither signed nor sealed the blessings of the covenant of Abraham to the individuals to whom it was by Divine appointment administered. It did not imply that they who were circumcised were accounted the heirs of the promises, either temporal or spiritual. It was not applied to mark them individually as heirs of the promises. It did not imply this even to Isaac and Jacob, who are by name designated heirs with Abraham. Their interest in the promises was secured to them by God’s expressly giving them the covenant, but was not represented in their circumcision. Circumcision marked no character, and had an individual application to no man but Abraham himself. It was the token of this covenant; and as a token or sign, no doubt applied to every promise in the covenant, but it did not designate the individual circumcised as having a personal interest in these promises. The covenant promised a numerous seed to Abraham; circumcision, as the token of that covenant, must have been a sign of this; but it did not sign this to any other. Any other circumcised individual, except Isaac and Jacob, to whom the covenant was given by name, might have been childless.
“Circumcision did not import to any individual that any portion of the numerous seed of Abraham should descend through him. The covenant promised that all nations should be blessed in Abraham—that the Messiah should be his descendant. But circumcision was no sign to any other that the Messiah should descend from him,—even to Isaac and Jacob this promise was peculiarly given, and not implied in their circumcision. From some of Abraham’s race, the Messiah, according to the covenant, must descend, and circumcision was a sign of this: but this was not signed by circumcision to any one of all his race. Much less could circumcision ‘sign’ this to the strangers and slaves who were not of Abraham’s posterity. To such, even the temporal promises were not either ‘signed’ or sealed by circumcision. The covenant promised Canaan to Abraham’s descendants, but circumcision could be no sign of this to the strangers and slaves who enjoyed no inheritance in it” (Alexander Carson, 1860). That circumcision did not seal anything to anyone but to Abraham himself is established beyond shadow of doubt by the fact that circumcision was applied to those who had no personal interest in the covenant to which it was attached. Not only was circumcision administered by Abraham to the servants and slaves of his household, but in Genesis 17:23 we read that he circumcised Ishmael, who was expressly excluded from that covenant! There is no evading the force of that, and it is impossible to reconcile it with the views so widely pervading upon the Abrahamic covenant. Furthermore, circumcision was not submitted to voluntarily, nor given with reference to faith, it was compulsory, and that in every instance: “He that is born in thy house, and he that is bought with thy money must needs be circumcised” (Gen. 17:13)— those refusing, being “cut off from his people” (v. 14). How vastly different was that from Christian baptism!
-Pink, Arthur W. (2010-03-19). The Divine Covenants (Kindle Locations 2167-2186). . Kindle Edition.
The Old Covenant is coextensive with and collectively representative of theocratic Israel, defined by the Abrahamic, conditioned by the Mosaic, and focused by the Davidic Covenants. The Old Covenant, and thus each of these three covenants, differs from the New Covenant not merely in administration, but also in substance.
Nehemiah Coxe helps draw out the implications of this for circumcision:
Yet this restipulation [meaning counter-engagement or covenant response] (and consequently, the way and manner of obtaining covenant blessings, as well as the right by which we claim them) necessarily varies according to the different nature and terms of those covenants that God at any time makes with men. If the covenant be of works, the restipulation must be by doing the things required in it, even by fulfilling its condition in a perfect obedience to its law. Suitably, the reward is of debt according to the terms of such a covenant. (Do not understand it of debt absolutely but of debt by compact [Coxe is referring to covenantal merit here].) But if it be a covenant of free and sovereign grace, the restipulation required is a humble receiving or hearty believing of those gratuitous promises on which the covenant is established. Accordingly, the reward or covenant blessing is immediately and eminently of grace.
-Nehemiah Coxe, Covenant Theology from Adam to Christ p. 39
So, when we look at the Abrahamic Covenant, did Abraham only have to believe? Or were works required? Coxe elaborates:
We will now pass on to Genesis 17. What is more largely recorded there, is briefly pointed at by Stephen in his general view of the history of Israel (Acts 7:8), “and he gave him the covenant of circumcision; and so Abraham became the father of Isaac,” etc. By the covenant of circumcision we are to understand that covenant of which a restipulation was required by the observation of this rite or ordinance, as in Genesis 17:9-11.
It is noteworthy that in this transaction of God with Abraham we first meet with an express injunction of obedience to a command (and that of positive right) as the condition of covenant interest. It is all ushered in with this prologue (Genesis 17:1), “I am the Almighty God; walk before me and be perfect.” First in these words, the all-sufficiency of God is revealed for the ensuring of the promises. Then a strict and entire obedience to his precepts is required in order to inherit the good things that were to be given by this covenant. In this mode of transacting it, the Lord was pleased to draw the first lines of that form of covenant relationship in which the natural seed of Abraham was fully stated by the law of Moses, which was a covenant of works with its condition or terms, “Do this and live.” p. 91
At present it will suffice to remind you that there is no way of avoiding confusion and entanglements in our conception of these things except by keeping before our eyes the distinction between Abraham’s seed as either spiritual or carnal, and of the respective promises belonging to each. For this whole covenant of circumcision given to the carnal seed, can no more convey spiritual and eternal blessings to them as such, than it can now enright a believer (though a child of Abraham) in their temporal and typical blessings in the land of Canaan. Neither can I see any reason for assigning a covenant interest in all typified spiritual blessings (as well as in the temporal blessings that were the types of them) to the carnal seed, and yet not admit the same covenant to convey temporal blessings to the spiritual seed. I say this since some conceive both are directly included in the same covenant and the promise of both was sealed with the same seal.
But the truth is, despite the relationship this covenant has to the covenant of grace, it yet remains distinct from it. It can give no more than external and typical blessings to a typical seed. The proper end and design of this transaction in Genesis 17 is the stating of their rights and privileges in a subordinate and typical relation to the dispensation of grace to the elect in the new covenant…
This covenant of circumcision was the foundation on which the church-state of Israel after the flesh was built. I do not say that their church-state was exactly and completely formed by this ordinance alone. But I mean that in the covenant of circumcision were contained the first rudiments of the one in the wilderness, and the latter was the filling up and completing of the former. It was made with them in pursuance of it and for the full accomplishment of the promises now made to Abraham. And therefore the privilege of the carnal seed of Abraham by virtue of the covenant of circumcision can rise no higher than the advantage and privilege of a Jew by virtue of the covenant in the wilderness.
To confirm this I will offer these things. First, circumcision was the entrance into and boundary of communion in the Jewish church. It was made so by the express command of God himself, who strictly enjoined that whoever broke the covenant by the neglect of circumcision should be cut off from his people (Gen 17:14). As it was to them a gate of privilege, so it was no less a bond of duty. It not only obliged them to obey the will of God so far as it was now made known to Abraham, but also, to the observation of all those laws and ordinances that were delivered later to them by Moses. For the circumcised person was a debtor to keep the whole law (Gal 5:3). This obligation resulted from its proper use and end in its primitive institution. For we do not read of its appointment to any new end by Moses, nor of any use it was assigned, de novo, which it did not have (at least virtually) from its first appointment. It was from first to last, a visible character on this people as separated to God from other nations, and as such they made their boast of it. Therefore it may be concluded to belong to that covenant from which all their rights and privileges as a people sprang. And where the sign was not varied, there was no essential variation or change in the covenant itself…
Moreover, it is notable that immediately after, in continuing his discourse in Romans 4, the apostle refers circumcision to the law in contradistinction from the gospel. For when he has told us that the circumcised Jew could not obtain the blessing of a spiritual relationship to Abraham by virtue of his circumcision, unless he walked in the steps 1 of Abraham’s faith which he had while uncircumcised, verse 12, he assigns this as the reason of it in the 13th verse. For the promise that he should be the heir of the world was not to Abraham or to his seed through the law, but through the righteousness of faith. And I cannot see how the conclusion which the apostle makes concerning the inefficacy of circumcision is enforced by this reason, if circumcision immediately and in its own nature had not belonged to the law but to the righteousness of faith or covenant of grace, as an ordinary seal of it.
The interpretation made of this text is further strengthened by comparing other places in the New Testament where we find that circumcision is styled an unsupportable yoke (Acts 15:10) and is said to lay men under an obligation to keep the whole law (Galatians 5:3). The complete dispensation of grace in the gospel according to the new covenant is constantly insisted on as that which renders it utterly useless to the gospel church and manifests the inconsistency of retaining its practice with the liberty of their present state. For instance, see the epistle to the Galatians 5:13. There the apostle tells them if he still preached circumcision, then the offence of the cross was ceased and he might have lived free from the persecutions he now suffered from the unbelieving Jews. It was the apostles preaching Christ, in which they asserted the shaking and removing of that old covenant to which circumcision belonged and by which the Jews held the right of their peculiar privileges that was the ground of the controversy between them and of their unreasonable opposition to him. For if the controversy had been about the mode of administering the same covenant, and the change only of an external rite by bringing baptism into the place of circumcision to serve for the same use and end now as that had done before, the heat of their contests might soon have been allayed. This is especially the case when we consider that the latter is far less painful and dangerous than the former. But he will certainly find himself engaged in a very difficult task who will seriously endeavor to reconcile the apostles’ discourses of circumcision with such a notion of it. Circumcision was an ordinance of the old covenant and pertained to the law and therefore directly bound its subjects to a legal obedience. But baptism is an ordinance of the gospel and (besides other excellent and most comfortable uses) directly obliges its subjects to gospel obedience. Therefore it is in this respect opposed to, rather than substituted in the place of, circumcision.
Abraham had a twofold seed, natural, of the Jews; and faithful, of the believing Gentiles: his natural seed was signed with the sign of circumcision, first indeed for the distinguishing of them from all other Nations whilst they as yet were not the seed of Abraham, but especially for the memorial of the justification of the Gentiles by faith, when at length they should become his seed. Therefore circumcision was of right to cease, when the Gentiles were brought in to the faith, forasmuch as then it had obtained its last and chief end, & thenceforth circumcision is nothing.
Consider this in light of Meredith Kline’s observations
How Abraham’s obedience related to the securing of the kingdom blessings in their old covenant form is a special question within the broad topic of the role of human works under redemptive covenant…
But if the ground of Israel’s tenure in Canaan was their covenant obedience, their election to receive the typological kingdom in the first place was emphatically not based on any merit of theirs (cf. Deut 9:5, 6). Their original reception of this kingdom, as well as their restoration to it after the loss of their national election in Babylonian exile, is repeatedly attributed to God’s remembrance of his promissory commitments of grace to Abraham, Isaac, and Jacob (Exod 2:24;3:6ff.; 6:2ff.; 32:13; Deut 9:27; 10:15; Lev 26:42), pointing to the coming Messiah and the new covenant.
When, however, we trace the matter back to the record of God’s covenant revelation to the patriarchs we encounter statements that connect the promissory grant of the kingdom to the faithful service rendered to the Lord by Abraham…
Here the significance of Abraham’s works cannot be limited to their role in validation of his own faith. His faithful performance of his covenantal duty is here clearly declared to sustain a causal relationship to the blessing of Isaac and Israel. It had a meritorious character that procured a reward enjoyed by others…
Because of Abraham’s obedience redemptive history would take the shape of an Abrahamite kingdom of God from which salvation’s blessings would rise up and flow out to the nations. God was pleased to constitute Abraham’s exemplary works as the meritorious ground for granting to Israel after the flesh the distinctive role of being formed as the typological kingdom, the matrix from which Christ should come. Within this typological structure Abraham emerges as an appointed sign of his promised messianic seed, the Servant of the Lord, whose fulfillment of his covenantal mission was the meritorious ground of the inheritance of the antitypical, eschatological kingdom by the true, elect Israel of all nations. Certainly, Abraham’s works did not have that status. They were, however, accorded by God an analogous kind of value with respect to the typological stage represented by the old covenant. Though not the ground of the inheritance of heaven, Abraham’s obedience was the ground for Israel’s inheritance of Canaan. Salvation would not come because of Abraham’s obedience, but because of Abraham’s obedience salvation would come of the Abrahamites, the Jews (John 4:22)…
The obedient Abraham, the faithful covenant servant, was a type of the Servant of the Lord in his obedience, by which he became the surety of the new covenant.