That is, They which are the children of the flesh, these are not the children of God: but the children of the promise are counted for the seed.

That is, it is not the children of the flesh that are children of God; but the children of the promise are reckoned for a seed.

That is to say, not they that are the children of the flesh, are the children of God; but they, that are the children of the promise, are accounted for the seed.

That is, they that are the children of the flesh, these are not the children of God; but the children of the promise are reckoned as seed.

In other words, it is not the children by natural descent who count as God's children, but the children made such by the promise are regarded as Abraham's posterity.

That is, it is not the children of the flesh, but the children of God's undertaking, who are named as the seed.

That is, it is not the children of the flesh who are children of God, but the children of the promise are counted as descendants.

In other words, those who are the sons of God are not those who are sons of the flesh, but those who are sons of the Promise; these are considered to be the offspring.

This means that it is not the children born in the course of nature who are God's children, but it is the children born in fulfillment of the Promise who are to be regarded as Abraham's descendants.

Hoc est, non qui sunt filii carnis, ii filii sunt Dei; sed qui sunt filii promissionis, censebuntur in semen:

That is, They are not, etc. He now gathers from God's answer a proposition, which includes the whole of what he had in view. For if Isaac, and not Ishmael, was the seed, though the one as well as the other was Abraham's son, it must be that all natural sons are not to be regarded as the seed, but that the promise is specially fulfilled only in some, and that it does not belong commonly and equally to all. He calls those the children of the flesh, who have nothing superior to a natural descent; as they are the children of the promise, who are peculiarly selected by the Lord.

They which are the children of the flesh - The natural descendants.
These are not the children of God - Are not of necessity the adopted children of God; or are not so in virtue of their descent merely. This was in opposition to one of the most settled and deeply cherished opinions of the Jews. They supposed that the mere fact of being a Jew, entitled a man to the blessings of the covenant, and to be regarded as a child of God. But the apostle shows them that it was not by their natural descent that these spiritual privileges were granted; that they were not conferred on people simply from the fact that they were Jews; and that consequently those who were not Jews might become interested in those spiritual blessings.
But the children of the promise - The descendants of Abraham on whom the promised blessings would be bestowed. The sense is, that God at first contemplated a distinction among the descendants of Abraham, and intended to confine his blessings to such as he chose; that is, to those to whom the promise particularly appertained, to the descendants of Isaac. The argument of the apostle is, that "the principle" was thus established that a distinction might be made among those who were Jews; and as that distinction had been made in former times, so it might be under the Messiah.
Are counted - Are regarded, or reckoned. God reckons things as they are; and therefore designed that they should be his true children.
As the seed - The spiritual children of God; the partakers of his mercy and salvation. This refers, doubtless, to spiritual privileges and to salvation; and therefore has relation not to nations as such, but to individuals.

That is, They which are the children of the flesh - Whence it appears that not the children who descend from Abraham's loins, nor those who were circumcised as he was, nor even those whom he might expect and desire, are therefore the Church and people of God; but those who are made children by the good pleasure and promise of God, as Isaac was, are alone to be accounted for the seed with whom the covenant was established.

(5) That is, They which are the children of the (k) flesh, these [are] not the children of God: but the children of the (l) promise are counted for the seed.
(5) A general application of the former proof or example.
(k) Who are born of Abraham by the course of nature.
(l) Who are born by virtue of the promise.

That is, they which are the children of the flesh,.... This is an explanation of the foregoing verse, and shows, that by "the seed of" Abraham are meant, the natural seed of Abraham, who are born after the flesh, or descend from him by carnal generation:
these are not the children of God; that is, not all of them, nor any of them, on account of their being children of the flesh, or Abraham's natural seed; for adoption does not come this way; men do not commence children of God by their fleshly descent; they are not "born of blood", but of God, who are the sons of God:
but the children of the promise are counted for the seed; "children of the covenant", is a common phrase with the Jews; who reckoned themselves as such, because they were the seed of Abraham: thus in their prayers they say (e) to God,
"we are thy people, , "the children of thy covenant", the children of Abraham thy friend.''
And so they were the children of the covenant, or promise, which God made with Abraham and his natural seed, respecting the land of Canaan, and their enjoyment of temporal good things in it; but they were not all of them the children of the promise, which God made to Abraham and his spiritual seed, whether Jews or Gentiles, respecting spiritual and eternal things; to whom alone the promises of God, being their God in a spiritual sense, of spiritual and eternal salvation by Christ, and of the grace of the Spirit of God, and of eternal life belong; and who are the seed which were promised to Abraham by God, saying, "thou shalt be a father of many nations", Genesis 17:4, for which reasons, because these spiritual promises belong to them, and because they themselves were promised to Abraham, as his children, therefore they are called "children of the promise": or rather, because as Isaac was a child of promise, being born after the Spirit, by virtue of the promise of God, through his divine power and goodness, when there were no ground or foundation in nature, for Abraham and Sarah to hope for a son; so these are called "children of promise", Galatians 4:28, because they are born again, not through the power of nature, and strength of their own free will; they are not born of the will of the flesh, nor of the will of man, but of God, according to the will of God and his abundant mercy, by the word of truth, through his power, Spirit, and grace; and by faith receive the promises made unto them; and are counted and reckoned as "Abraham's seed, and heirs according to the promise", Galatians 3:29, whether they be Jews, or whether they be Gentiles: and since now the promises of God are all made good to these persons, the word of God is not without effect, or is not made void, by the casting off the children of the flesh, or the carnal seed of Abraham, who were not children of the promise in the sense now given.
(e) Seder Tephillot, fol. 3. 2. Ed. Basil. fol. 6. 1. Ed. Amstelod.

That is, Not the children, &c. - As if he had said, This is a clear type of things to come; showing us, that in all succeeding generations, not the children of the flesh, the lineal descendants of Abraham, but the children of the promise, they to whom the promise is made, that is, believers, are the children of God. Genesis 21:12