For if God spared not the natural branches
That is, executed his righteous judgments, inflicted due punishment upon the Jews, unchurched them, and stripped them of those privileges they enjoyed in a church state; who were the natural descendants of Abraham; were naturally, and as born into the world, in a national church state and in that national covenant God made with that people; to whom belonged a national adoption, in which sense they were the sons of God, his firstborn; they were chosen by him as a special and peculiar people, to very great favours and privileges; they were Christ's own, he came of them according to the flesh, and was particularly sent unto them, and ministered among them; wherefore, if, at last, God did not spare this people, though he had for a long time done it, but stirred up all his wrath against them, they disbelieving his Son, rejecting and despising the Messiah, and salvation by him, this should awaken the fear, care, and caution of the Gentiles in a church state, lest if they behave not well, he should deal in like manner with them:
take heed lest he also spare not thee;
for whatever was done to the Jews in former or latter times, are written for the instruction and admonition of Gentiles; and the use they are to make thereof is, to be careful and cautious, lest by imbibing principles derogatory from the grace of God and glory of Christ, or by an unbecoming walk and conversation they provoke the Lord to unchurch them as he has done the Jews before them; and which they may the rather fear, since the Jews were the natural branches, and they formerly strangers and aliens.