Cool
Which "translation" are you using?
The Bible says to fulfill the word of God.
You agreed that being made join-heirs with Christ was not found in the OT, but now you're saying that it was already revealed?
God gave Paul revelation of things HID IN GOD.... that means that NOBODY knew those things until it was revealed to Paul. Paul did NOT keep it a secret, but revealed it to others.
There were people who knew! The Gentiles did not know but there were Jews who knew!
The Samaritan woman at the well.
John the baptizer.
This is PETER speaking about GENTILES can be saved too:
Acts 10:43 All the prophets testify about him that
everyone who believes in him receives forgiveness of sins through his name."
Jesus preached it:
Luke 24:46 He told them, “This is what is written: The Messiah will suffer and rise from the dead on the third day, 47
and repentance for the forgiveness of sins will be preached in his name to all nations, beginning at Jerusalem. 48 You are witnesses of these things.
Luke 24:47 and repentance for the forgiveness of sins will be preached in his name to all nations, beginning at Jerusalem.
2 Samuel 22:50 Therefore I will praise you, LORD, among the nations; I will sing the praises of your name.
Psalm 117:1 Praise the LORD, all you nations; extol him, all you peoples.
Apostle Paul even quotes Psalm 117:1 to let the Gentiles know that it was said in the Old Testament that they would be brought near to God one day.
Romans 15:11 And again, "Praise the Lord, all you Gentiles; let all the peoples extol him."
Psalm 66:4 All the earth bows down to you; they sing praise to you, they sing the praises of your name."
John 4:42 They said to the woman, “We no longer believe just because of what you said; now we have heard for ourselves, and we know that this man really is the Savior of the world.”
John 1:29 The next day John saw Jesus coming toward him and said, "Look, the Lamb of God, takes away the sin of the world!
1 John 2:2 He is the atoning sacrifice for our sins, and not only for ours but also for the sins of the whole world.
1 John 4:14 And we have seen and testify that the Father has sent his Son to be the Savior of the world.