11. Ye shall circumcise the flesh of your foreskin. Very strange and unaccountable would this command at first sight appear. The subject treated of, is the sacred covenant, in which righteousness, salvation, and happiness are promised; whereby the seed of Abraham is distinguished from other nations, in order that it may be holy and blessed; and who can say that it is reasonable for the sign of so great a mystery to consist in circumcision? But as it was necessary for Abraham to become a fool, in order to prove himself obedient to God; so whosoever is wise, will both soberly and reverently receive what God seems to us foolishly to have commanded. And yet we must inquire, whether any analogy is here apparent between the visible sign, and the thing signified. For the signs which God has appointed to assist our infirmity, should be accommodated to the measure of our capacity, or they would be unprofitable. Moreover, it is probable that the Lord commanded circumcision for two reasons; first, to show that whatever is born of man is polluted; then, that salvation would proceed from the blessed seed of Abraham. In the first place, therefore, whatever men have peculiar to themselves, by generation, God has condemned, in the appointment of circumcision; in order that the corruption of nature being manifest, he might induce them to mortify their flesh. Whence also it follows, that circumcision was a sign of repentance. Yet, at the same time, the blessing which was promised in the seed of Abraham, was thereby marked and attested. If then it seem absurd to any one, that the token of a favour so excellent and so singular, was given in that part of the body, let him become ashamed of his own salvation, which flowed from the loins of Abraham; but it has pleased God thus to confound the wisdom of the world, that he may the more completely abase the pride of the flesh. And hence we now learn, in the second place, how the reconciliation between God and men, which was exhibited in Christ, was testified by this sign. For which reason it is styled by Paul a seal of the righteousness of faith. (Rom. 4:11.) Let it suffice thus briefly to have touched upon the analogy between the thing signified and the sign.
12. And he that is eight days old shall be circumcised. God now prescribes the eighth day for circumcision; whence it appears that this was a part of that discipline, under which he intended to keep his ancient people; for greater liberty is, at this day, permitted in the administration of baptism. Some, however, maintain that we must not contend earnestly about the number of days, because the Lord spared the children on account of their tenderness, since it was not without danger to inflict a wound upon those who were newly born. For although he might have provided that circumcision should produce no harm or injury; yet there would be no absurdity in saying, that He had respect to their tender age, in order to prove to the Jews his paternal love towards their children. To others this seems to be too frigid; therefore they seek a spiritual mystery in the number of days. They think that the present life is allegorically signified by the seven days; that God commanded infants to be circumcised on the eighth day, in order to show that though we must give attention to the mortification of the flesh during the whole course of our life, it will not be completed till the end. Augustine also thinks that it had reference to the resurrection of Christ; whereby external circumcision was abolished, and the truth of the figure was set forth. It is probable and consonant with reason, that the number seven designated the course of the present life. Therefore the eighth day might seem to be fixed upon by the Lord, to prefigure the beginning of a new life. But because such a reason is never given in Scripture, I dare affirm nothing. Wherefore, let it suffice to maintain what is certain and solid; namely, that God, in this symbol, has so represented the destruction of the old man, as yet to show that he restores men to life.
He that is born in the house, or bought with money. When God commands Abraham to circumcise all whom he has under his power, his special love towards holy Abraham is conspicuous in this, that He embraces his whole family in His grace. We know that formerly slaves were scarcely reckoned among the number of men. But God, out of regard to his servant Abraham, adopts them as his own sons: to this mercy nothing whatever can be added. The pride also of the flesh is cast down; because God, without respect of persons, gathers together both freemen and slaves. But in the person of Abraham, he has prescribed it as a law to all his servants, that they should endeavour to bring all who are subject to them, into the same society of faith with themselves. For every family of the pious ought to be a church. Therefore, if we desire to prove our piety, we must labour that every one of us may have his house ordered in obedience to God. And Abraham is not only commanded to dedicate and to offer unto God those born in his house, but whomsoever he might afterwards obtain.
13. For an everlasting covenant. The meaning of this expression may be twofold: either that God promises that his grace, of which circumcision was a sign and pledge, should be eternal; or that he intended the sign itself to be perpetually observed. Indeed, I have no doubt that this perpetuity ought to be referred to the visible sign. But they who hence infer, that the use of it ought to flourish among the Jews even of the present time, are (in my opinion) deceived. For they swerve from that axiom which we ought to regard as fixed; that since Christ is the end of the law, the perpetuity which is ascribed to the ceremonies of the law, was terminated as soon as Christ appeared. The temple was the perpetual habitation of God, according to that declaration, “This is my rest for ever, here will I dwell,” (Ps. 132:14.) The Sabbath indicated not a temporal but a perpetual sanctification of the people. Nevertheless, it is not to be denied, that Christ brought them both to an end. In the same way must we also think of circumcision. If the Jews object, that in this manner, the law was violated by Christ; the answer is easy; that the external use of the law was so abrogated, as to establish its truth. For, at length, by the coming of Christ, circumcision was substantially confirmed, so that it should endure for ever, and that the covenant which God had before made, should be ratified. Moreover, lest the changing of the visible sign should perplex any one, let that renovation of the world, of which I have spoken, be kept in mind; which renovation—notwithstanding some interposed variety—has perpetuated those things which would otherwise have been fading. Therefore, although the use of circumcision has ceased; yet it does not cease to be an everlasting, or perpetual covenant, if only Christ be regarded as the Mediator; who, though the sign be changed, has confirmed the truth. And that, by the coming of Christ, external circumcision ceased, is plain from the words of Paul; who not only teaches that we are circumcised by the death of Christ, spiritually, and not through the carnal sign: but who expressly substitutes baptism for circumcision; (Col. 2:11;) and truly baptism could, not succeed circumcision, without taking it away. Therefore in the next chapter he denies that there is any difference between circumcision and uncircumcision; because, at that time, the thing was indifferent, and of no importance. Whence we refute the error of those, who think that circumcision is still in force among the Jews, as if it were a peculiar symbol of the nation, which never ought to be abrogated. I acknowledge, indeed, that it was permitted to them for a time, until the liberty obtained by Christ should be better known; but though permitted, it by no means retained its original force. For it would be absurd to be initiated into the Church by two different signs; of which the one should testify and affirm that Christ was come, and the other should shadow him forth as absent.
John Calvin and John King, Commentary on the First Book of Moses Called Genesis, vol. 1, 453–457.