Blessed Paul was appointed a minister of the divine gospel (cf. Rom 1:1). He proclaimed Christ to the Gentiles, saying everywhere that those of Israel's blood had fallen away. He affirmed that those once in demonic darkness had become servants called according to God's foreordination and foreknowledge.
Therefore, lest some unlearned person think that he was almost trampling those cast down from Israel's race and mocking the fallen, he offers the necessary defense and says: "I speak the truth in Christ, I do not lie," and what follows.
One may indeed grieve over those who reached such folly that they withdrew from love for God and then suffered punishments for this. It would not be unreasonable to shed tears over them from kindred love. Rather, in this is the fullness of love.
Yet to wish oneself to be cut off from Christ for their sake finally goes beyond love. No one, if he is of sound mind, would dare oppose God for the salvation of others, count his own life as nothing, and prefer that it belong to others.
What, then, does he mean by offering his own salvation as a ransom for the salvation of the Jews? Clearly this speech is hyperbolic and contains the declaration of most perfect love. "I could wish," he says, "that I myself were accursed from Christ for my brethren, my kinsmen according to the flesh."
It is as though he were saying: "If Israel were saved again through my opposition to Christ, I, who said to those justified in faith, 'I determined not to know anything among you except Jesus Christ and Him crucified' (1 Cor 2:2), and who proclaim to all, 'Who shall separate us from the love of God? Shall tribulation, or distress, or persecution, or famine, or nakedness, or peril, or sword?' (Rom 8:35), would choose to take upon myself such a dreadful evil and alone go to perdition for all."
By this he was catching the Jews into obedience and repelling the slander of the senseless. Some of the Jews thought that the divine Paul, having lost his reason, opposed the laws given through Moses. For this reason, writing to believers, he said: "For if we are beside ourselves, it is for God; if we are of sound mind, it is for you" (2 Cor 5:13).
Thus, he says, I would most gladly prefer, in order to save again those who sprang from Israel's blood, to be cut off from Christ.
He does not stop there. He shows that the cause of his grief over them is by no means slight. It could produce in him such a disposition that he would not regard it as grievous or absurd to say that he offers his own life as a ransom for the life of others.
For first, he says, they are Israelites. To them belong the adoption, the glory, and the covenants. From them, according to the flesh, is Christ Himself.
If they were among those who had only recently come to know Him Who is God by nature and in truth, the sorrow over them could be more moderate. If they had not possessed the law given through Moses, which crowned them with nearness to Him, the sorrow could be more moderate.
If they had not sprung from the root of the holy fathers and had not been appointed heirs of their glory, the sorrow could be more moderate. If they had not been the first taught the ways of serving God, the sorrow could be more moderate.
But if these are their fathers and the rest, and if, while their affairs were almost carried by a fair wind, they strayed toward an unexpected end and did not attain what they hoped for, is not what befell these wretched ones truly terrible?