Romans 9:33

as it is written, Behold, I lay in Sion a stumbling-stone and rock of offense; and whosoever believeth on Him shall not be ashamed.

The apostle had shown that God was building His Church by calling His own from among the Gentiles and from a small remnant of Israel, the great majority of the Jewish people, the nation as such, being rejected. What conclusion is to be drawn from these facts, which agreed exactly with the prophecies? Paul brings the answer in the form of a paradox, in which the words sound like a contradiction: The Gentiles, which have not followed after righteousness, obtained righteousness, but the righteousness of faith. The Gentiles made no attempt to become perfect by the keeping of the Law, they did not concern themselves about the righteousness of life as required by God's holy Law. But in the Word of the Gospel the righteousness was placed before them, not that they were made holy and perfect, but that they were given righteousness by faith. God wrought faith in their hearts through the Gospel, and through this faith they seized righteousness; God declared them to be righteous, He looked upon them as though they were perfectly pure and righteous. And this fact the apostle mentions for the sake of emphasizing the condition of the Jews. But Israel, following after, earnestly seeking, the law of righteousness, did not attain to that law. The Jews had the Mosaic Law, and they believed that they could fulfill this Law perfectly and thus obtain the righteousness which would make them acceptable before God through their works. But all these efforts proved futile; Israel did not come up to the demands of the Law, it could not come up to the requirements which it sought. An external veneer of right living the Jews managed to acquire, but the true spiritual fulfillment of the Law they did not attain. Since, however, perfect righteousness is a condition of salvation, the rejection of the Jews, wrath and condemnation, followed as a matter of course.

And the connection is brought out in the last verses. Why did Israel never attain to that point that it was in perfect agreement with the Law? Why did the Jews fail to secure righteousness? Because they sought after it not by faith, but, as people will commonly say, as though they could obtain it, by works of the Law. The Law being inadequate for the needs of the sinners, God had proposed a method of justification which alone was suitable for sinners. But of this they were willfully ignorant; they rejected the perfect righteousness prepared for them; they refused to accept the Gospel of Jesus Christ. And thus they stumbled over the stone of offense, the Messiah Himself; as had been predicted, they took offense at the plan of salvation revealed in Jesus Christ and made possible by His vicarious sacrifice. They stumbled over Him and thereby came to grief. And thus the prophecy of Isaiah 28:16; Isaiah 8:13, was fulfilled, as its content is briefly given by Paul: Behold, I lay in Zion a stone of stumbling and a rock of offense, and he that believes on Him shall not be put to shame. The precious stone which the Lord laid as a foundation and corner-stone in His spiritual temple is Jesus, the only Source of salvation. But Israel has repudiated the redemption of this Messiah, and therefore He has become to the disobedient, unbelieving people a stone of stumbling and a rock of offense. That is God's judgment upon the willful despisers of His grace and method of salvation: they take offense at Christ and the Gospel and thus are finally brought to a point where they can no longer accept the redemption and are given up to condemnation and destruction. Note: He that rejects the plan and method of salvation proposed by God, and tries to obtain righteousness by his own works and fulfillment of the Law, will find himself in the position of the unbelieving Jews and will share their condemnation.

Summary

The apostle shows that the promise of God to the patriarchs had not been without effect, but had found its application in the spiritual children of Abraham; that God indeed has sovereign power to show mercy and to harden, but that he actually has shown great patience toward the disobedient people, and has gathered His Church out of Gentiles and Jews, the nation as such being rejected on account of its repudiation of the Messiah.