But Sarah, which denotes the state of the gospel, that new city which Christ hath brought from heaven with him (see note [b] Rev. xxi.), of which all we Christians are free-men or citizens, she is a freewoman, and signifies that we Christians, Gentiles as well as Jews, are free from the Mosaical rites, &c., and that we may be justified without them. According to that prophecy, Isa. liv. 1, Rejoice &c. the meaning of which is, that the gospel covenant, which when Christ was here on earth had few children, few that were brought forth by it, after his death, upon the preaching of the gospel by the apostles to the Gentiles, had many more than among the Jews in his lifetime. But, my brethren, as Isaac was born only by strength of God's promise, not by any ordinary means, Abraham and Sarah being beyond age, so are the children of God received to be such, and justified only by the promise of God, (that is, through the strength of that promise to Abraham and covenant in Christ, that all faithful, obedient, persevering believers should be justified,) without any Mosaical performances. But as Ismael then, who was born by the strength of nature, persecuted him that was born by the strength of God's promise only, viz. Isaac, so now it comes to pass; they that depend on the law for justification, persecute them that depend only on God's promise, that are persuaded that through faith, without legal performances, they shall be justified. To these therefore is applicable that which follows in the story, that Ismael is to be cast out, and none but Isaac to inherit: they that depend on the law for justification never attain to it, but they that depend on the sole promise of God, and accordingly expect to be justified upon performance of sincere evangelical obedience, without necessity of legal performances, they only shall be heirs of this mercy.