John 8:39

39.Abraham is our father. This altercation shows plainly enough how haughtily and fiercely they despised all Christ’s reproofs. What they continually claim and vaunt of is, that they are Abraham’s children; by which they do not simply mean that they are the lineal descendants of Abraham, but that they are a holy race, the heritage of God, and the children of God. And yet they rely on nothing but the confidence of the flesh. But carnal descent, without faith, is nothing more than a false pretense. We now understand what it was that so greatly blinded them, so that they treated Christ with disdain, though armed with deadly thunder. Thus the word of God, which might move stones, is ridiculed in the present day by Papists, as if it were a fable, and fiercely persecuted by fire and sword; and for no other reason but that they rely on their false title of “the Church,” and hope that they will be able to deceive both God and man. In short, as soon as hypocrites have procured some plausible covering, they oppose God with hardened obstinacy, as if he could not penetrate into their hearts.

If you were the children of Abraham, you would do the works of Abraham. Christ now distinguishes more plainly between the bastard and degenerate children of Abraham, and the true and lawful children; (236) for he refuses to give the very name to all who do not resemble Abraham True, it frequently happens that children do not resemble, in their conduct, the parents from whom they are sprung; but here Christ does not argue about carnal descent, but only affirms that they who do not retain by faith the grace of adoption are not reckoned among the children of Abraham before God. For since God promised to the seed of Abraham that he would be their God, saying,

I will establish my covenant between me and thee, and thy seed after thee, in their generations, for an everlasting covenant, to be a God unto thee, and to thy seed after thee,
(Genesis 17:7,)

all unbelievers, by rejecting this promise, excluded themselves from the family of Abraham.

The state of the question therefore is this: Ought they to be accounted Abraham’s children who reject the blessing offered to them in the word, so that, notwithstanding of this, they shall be a holy nation, the heritage of God, and a royal priesthood? (Exodus 19:6; Joel 3:2.) Christ denies this, and justly; for they who are the children of the promise must be born again by the Spirit, and all who desire to obtain a place in the kingdom of God ought to be new creatures. Carnal descent from Abraham was not indeed useless, and of no value, provided that the truth were added to it. For election dwells in the seed of Abraham, but it is free, so that all whom God sanctifies by his Spirit are accounted heirs of life.