Therefore the Jews should be troubled by nothing in their turning to Christ, especially not by the fact that the Greeks are received together with them. God lacks nothing, least of all readiness to give the kingdom to all, in which there are many mansions.
This should already have been well known to the Jews. The prophets Isaiah, Joel, and others clearly proclaimed God's readiness to receive all who turn to Him.
The passage from the prophet Isaiah cited by the Apostle about the saving power of faith concerns the precious stone in Zion. By this stone all the Jews understood Christ, the Messiah.
The words of the prophet Joel also refer to the times of the Messiah. They speak of the outpouring of the Spirit of God upon all who confess the Lord. Their continuation is: "And it shall come to pass that everyone who calls upon the name of the Lord shall be saved."
These words were cited by the holy Apostle Peter in his sermon. He delivered it when the Holy Spirit had just descended upon the Apostles, and when the Jews, seeing the Apostles' exultation under the action of the Holy Spirit, thought they were drunk.
In refutation of this, the Apostle Peter said: We are not drunk. Rather, this has been fulfilled in us which the prophet Joel foretold, saying: "Upon My servants and upon My handmaidens in those days I will pour out of My Spirit, and they shall prophesy."
Then he concluded: "Repent, and let each of you be baptized in the name of the Lord Jesus Christ for the remission of sins, and you shall receive the gift of the Holy Spirit" (Acts 2:16-38).
Saint John Chrysostom says the same, concluding his explanation of this passage: "Do you see how the Apostle deprives the Jews of every excuse? When justification, which is the most important thing of all, is so easy and so readily received through faith, and when otherwise, without faith, it is impossible even to be saved, is it not the height of folly to abandon what is accessible and easy, and to take up what is impossible?
"The Law is burdensome, but grace is light. The Law, with its countless conditions, does not save. Grace gives justification both as grace and as lawful. What, then, will those say in their defense who stubbornly oppose grace and cling to the Law without profit or purpose?"
Certainly those who were not stubborn could say nothing in defense of their unbelief. Therefore they believed and, confessing Christ, asked what they should do next in order to be saved. Receiving the answer that they must be baptized, they were baptized (Acts 2:37, 41; 16:30-33).
But those who persisted in unbelief always found various defenses for their unbelief. Therefore the Apostle next turns to review some of these defenses.
He dwells especially on the fact that the calling of all to salvation was so frequent, powerful, and manifold that even the Gentiles responded to it. By this they became a spur to the Jews in their conversion to the Lord and Savior.
To give his words greater firmness, he again cites testimonies from the Old Testament.