“…by revelation He made known to me the mystery (as I have briefly written already, by which, when you read, you may understand my knowledge in the mystery of Christ), which in other ages was not made known to the sons of men, as it has now been revealed by the Spirit to His holy apostles and prophets: that the Gentiles should be fellow heirs, of the same body, and partakers of His promise in Christ through the gospel, of which I became a minister according to the gift of the grace of God given to me by the effective working of His power” (Eph 3:3–7).
It is well known that Paul said that the Church, the Body of Christ, was a mystery which was not made known in previous times. But does that mean that the Church is not prophesied in the OT?
See this article where Dr. John Walvoord argues that the mystery was not “partially revealed in the Old Testament.”
I believe that the Church was indeed prophesied in the OT and in the teachings of Jesus as well.
First, the OT anticipates a time when many Gentiles would come to faith in Messiah and that the Jewish people would be provoked to jealousy as a result. While a reader of the OT did not have enough information to understand that the Gentiles would be part of a body known as the Church and that this body would have both Jews and Gentiles within it and with equal standing, that doesn’t change the fact that the Church was prophesied. Paul points this out in Rom 10:18-21.
Second, there are types of the Rapture in the OT. God took Enoch and Elijah alive into heaven (Gen 5:24; 2 Kings 2:11). Lot and his wife and daughters were delivered before Sodom was destroyed (Gen 19:12-22). While no OT reader could have known that these events foreshadowed the coming Rapture of the Church, the revelation is present.
(See also this article which suggests that there are obscure references to the Rapture in the OT.)
Third, the Lord Jesus ministered during the OT era. The Church had not yet been born. Paul had not yet been given the mystery. Yet the Lord taught about the Rapture before the mystery of the Church, and the Rapture was revealed to the Apostles. See Matt 24:40-44; John 14:3.
Fourth, Psalm 45 presents Israel and the Church. I once heard a message by Zane Hodges on this Psalm. He powerfully showed that the two different groups of women in the Psalm represent Israel and the Church. The King in Psalm 45 is God’s Son, the Lord Jesus Christ. Note v 9: “Kings’ daughters are among Your honorable women; at Your right hand stands the queen in gold from Ophir.”
The kings’ daughters refer to Israel. The queen refers to the Church.
Note that in v 10 the Psalmist says to the queen, “Listen, O daughter, consider and incline your ear; forget your own people also, and your father’s house; so the King will greatly desire your beauty; because He is your Lord, worship Him.”
Was Israel to “forget your own people also, and your father’s house”? Hardly. Church-Age saints are to have our primary loyalty not to our ethnic heritage (Serbian, Kenyan, Cuban, Australian, Chinese, etc.) or to the country of our citizenship, but to the Lord Jesus Christ and to His Body, the Church. In that sense we are to forget our own people and our father’s house.
Of course, no OT saint reading Psalm 45 could have understood that this was talking about the Church, in which Jews and Gentiles would be united in one Body. However, with later revelation that becomes evident.
Fifth, in Matt 18:15-20 the Lord teaches about the coming Church and Church discipline. Note v 17, “And if he refuses to hear them, tell it to the church. But if he refuses even to hear the church, let him be to you like a heathen and a tax collector.” I realize that no one hearing that understood that Jesus was speaking about a group called “the Church” which would be made up of Jews and Gentiles united in one Body. However, in light of later revelation, that is clearly what the Lord was talking about.
It should be noted that some do not think that Matthew 18 talks about the Church or Church discipline. But most do think so. However, if this speaks of the Church and Church discipline, then the mystery was prophesied before Peter, Paul, and the other Apostles received the revelation needed to unlock the mystery.
The problem comes from a misunderstanding of what the word mystery (mustērion) means.
The word mystery occurs 21 times in Paul’s writings. He lists the following things as mysteries: the Rapture (1 Cor 15:51), Christ (Col 1:26; 2:2), the gospel (Eph 6:19), lawlessness (2 Thess 2:7), the faith (1 Tim 3:9), godliness (1 Tim 3:16), Babylon (Rev 17:5), and the Church (Eph 3:3-7; 5:32). Of course, those things are prophesied and even manifested many times in the Old Testament. But without further revelation those the specific meaning of those references remained a mystery.
A mystery is something which cannot be understood without further information. If you read a murder mystery, obscure clues are given early on as to who the murderer is. But those early clues are not sufficient to solve the mystery. Only when sufficient revelation is given can the mystery be solved. Peter did not understand that Gentiles were to be included in the Church until he received a vision from God (Acts 9-10). Paul did not understand that the Gentiles were to be included in the Church until he too received special revelation (Eph 3:3).
But the clues were there all along.
I am a Dispensationalist. I realize that most classic Dispensationalists consider it an article of faith that the Church was not prophesied in the OT. I do not agree. The Church is spoken about in the OT. However, apart from the later revelation of the NT no one would be able to understand that.