Does “the mystery” (Eph. 3: 3) mean nothing more than God widening His blessing beyond the Jew to include the Gentiles?
There were exceptional cases in the OT of Gentile blessing such as Ruth and Naaman, but nothing like the unprecedented outpouring of grace that has taken place since the Spirit fell upon Cornelius in Acts 10. This latter phenomenon, many allege, is what Paul had in mind when he spoke of the mystery—a “mystery among the nations, which is Christ in you” (that is, the nations) “the hope of glory” (Col. 1: 27). However, if the mystery simply means that the Gentiles are brought into blessing, then there would have to be no mention of such blessing in the OT. Why? Because “in other generations”, the mystery was not “made known to the sons of men” (Eph. 3: 5; see also Col. 1: 26). The mystery is a secret—that is what the word means—and if the substance of that secret was prophesied in the OT, then it never was a secret! So what does the OT revelation say?
“Since Abraham shall indeed become a great and mighty nation; and all the nations of the earth shall be blessed in him” (Gen. 18: 18). “All the ends of the earth shall remember and turn unto Jehovah, and all the families of the nations shall worship before thee ... All nations whom thou hast made shall come and worship before thee, O Lord, and shall glorify thy name” (Ps. 22: 27; 86: 9). “And it shall come to pass in the end of days, [that] the mountain of Jehovah’s house shall be established on the top of the mountains … and all the nations shall flow unto it. And many peoples shall go and say, Come, and let us go up to the mountain of Jehovah, to the house of the God of Jacob; and he will teach us of his ways, and we will walk in his paths … I have even given thee for a light of the nations, that thou mayest be my salvation unto the end of the earth … And the nations shall walk by thy light, and kings by the brightness of thy rising” (Is. 2: 2, 3; 49: 6; 60: 3). “At that time they shall call Jerusalem the throne of Jehovah; and all the nations shall be gathered unto it, to the name of Jehovah, to Jerusalem; and they shall no more walk after the stubbornness of their evil heart” (Jer. 3: 17). “And many nations shall join themselves to Jehovah in that day, and shall be unto me for a people” (Zech. 2: 11). “For from the rising of the sun even unto its setting my name shall be great among the nations; and in every place incense shall be offered unto my name, and a pure oblation” (Mal. 1: 11).
While this list is not exhaustive, it is utterly conclusive that the future blessing of the Gentiles was not a secret, but clearly revealed in the old dispensation. Thus if the mystery is simply Gentile blessing then Paul is talking nonsense when he says that he completed the Word of God by making the mystery known (see Col. 1: 25)! Nor is he contradicting himself when he says that the means by which it was made known was by “prophetic scriptures” (Rom. 16: 26), for Eph. 3: 5 makes clear that the reference is to NT not OT prophets.
In Acts 10, Peter’s preaching to the first Gentile converts to Christianity included the words “To him all the prophets bear witness that every one that believes on him will receive through his name remission of sins” (Acts 10: 43, my emphasis). That salvation was available to both Jew and Gentile, was, according to Peter, prophesied in “all the prophets”. Acts 15: 14–18 is similar. Neither of these passages can refer to a mystery “hidden throughout the ages in God” (Eph. 3: 9). Paul himself justified his turning to the nations by quoting Isaiah 49: 6 (see Acts 13: 46, 47), but again, this cannot be the mystery, for it was “by revelation” that the mystery was “made known” to him (Eph. 3: 3).I do not doubt that the mystery includes the thought of Gentile blessing, but Gentile blessing does not define it, nor is Gentile blessing exclusive to it (see Rev. 7: 9–17). Gentile blessing, as envisaged in the OT, was always on the basis of association with, and subservience to the Jew (see Zech. 8: 23). Those prophecies will be fulfilled in the world to come, in which Israel and Jerusalem will be preeminent. Gentile blessing in the mystery, however, is Jew and Gentile in united in one body to the Head in heaven. That, is what makes the mystery distinctive. Thus Jew and Gentile are “made both one”, “one new man” and “one body”, have access by “one Spirit to the Father”, are “fellow–citizens of the saints” and are “built together” (Eph. 2: 14–22). Again, those of the nations are described as “joint heirs” (that is, with the Jews), “a joint body” and “joint partakers” (Eph. 3: 6). That the Gentiles were to be blessed was nothing new—such blessing had been long prophesied. What was new, was that the Gentiles were to be placed on an equal footing with the Jew in one body, the body of Christ. That, is the mystery.