I was talking about the gospel.Then what did, and why?
Paul said something distinctive about his ministry had not before been revealed by God to anyone, but had been revealed THROUGH (not "by") Paul.
Do you know what that previously hidden information (musterion) was?
Start with Jesus. Read about Him. Learn even about the use of the term gospel.
There are the twelve apostles. The twelve disciples.
Paul is considered an apostle as well. Paul did preach the gospel, and his gospel. You can also read about the life of Paul.
From the words hidden and ages.
1 Corinthians 2:7 NASB - 7 but we speak God's wisdom in a mystery, the hidden wisdom which God predestined before the ages to our glory;
Ephesians 3:9 NASB - 9 and to bring to light what is the administration of the mystery which for ages has been hidden in God who created all things;
Colossians 1:26 NASB - 26 that is, the mystery which has been hidden from the past ages and generations, but has now been manifested to His saints,
See also: mystery.
This is what Jesus said to Ananias about Paul.
Acts 9:15-16 NASB - 15 But the Lord said to him, "Go, for he is a chosen instrument of Mine, to bear My name before the Gentiles and kings and the sons of Israel; 16 for I will show him how much he must suffer for My name's sake."
It is my hope and prayer that the scriptures become clear or plain to you. That you can see them for what they are.
Do you believe the Spirit of God was first poured out on believing Jews? I encourage you to read the Gospels and the Acts of the Apostles.