Look at how fast you change the subject! The mystery of Ephesians 3 is that Gentiles such as we, who in time past were without hope (Ephesians 2:11-12 KJV), now have hope (but now Ephesians 2:13 KJV) and can be fellowheirs, and of the same body, and partakers of his promise in Christ by the gospel (Ephesians 3:6 KJV). It was a mystery which in other ages was not made known unto the sons of men/ it was unsearchable in the OT/ a mystery hid in God/the fellowship of the mystery!
Ephesians 3:1 For this cause I Paul, the prisoner of Jesus Christ for you Gentiles,
Ephesians 3:2 If ye have heard of the dispensation of the grace of God which is given me to you-ward:
Ephesians 3:3 How that by revelation he made known unto me the mystery; (as I wrote afore in few words,
Ephesians 3:4 Whereby, when ye read, ye may understand my knowledge in the mystery of Christ)
Ephesians 3:5 Which in other ages was not made known unto the sons of men, as it is now revealed unto his holy apostles and prophets by the Spirit;
Ephesians 3:6 That the Gentiles should be fellowheirs, and of the same body, and partakers of his promise in Christ by the gospel:
Ephesians 3:7 Whereof I was made a minister, according to the gift of the grace of God given unto me by the effectual working of his power.
Ephesians 3:8 Unto me, who am less than the least of all saints, is this grace given, that I should preach among the Gentiles the unsearchable riches of Christ;
Ephesians 3:9 And to make all men see what is the fellowship of the mystery, which from the beginning of the world hath been hid in God, who created all things by Jesus Christ:
How do you ever get that I changed the topic?
Jesus is the mystery.
The Gentiles being included was known in the Old Testament times.
Prophecies of Jesus fulfilled, as shown by Gentiles believing in God---
so that the Gentiles may glorify God for his mercy, as it is written: “therefore I will praise you among the Gentiles; I will sing hymns to your name.”
Again, it says,
“Rejoice, O Gentiles, with his people.”
And again,
“Praise the Lord,
all you Gentiles,
And sing praises to him, all you
Peoples.”
And again, Isaiah says,
“The Root of Jesse will spring up,
one who will arise to rule over the
Nations;
The Gentiles will hope in him.”
Read this Old Testament scripture, it is quoted in the New Testament BY PAUL:
2 Samuel 22:50 Therefore I will praise you, LORD, among the nations; I will sing the praises of your name.
Romans 15:9
and, moreover, that the Gentiles might glorify God for his mercy. As it is written: "Therefore I will praise you among the Gentiles; I will sing the praises of your name."
...And these scriptures:
Romans 15:11
And again, "Praise the Lord, all you Gentiles; let all the peoples extol him."
Psalm 117:1 Praise the LORD, all you nations; extol him, all you peoples.
Psalm 66:4 All the earth bows down to you; they sing praise to you, they sing the praises of your name."