Jesus is a mystery

Ephesians 3:

4 When you read this you can perceive my insight into the mystery of Christ, 5 which was not made known to the sons of men in other generations as it has now been revealed to his holy apostles and prophets by the Spirit; 6 that is, how the Gentiles are fellow heirs, members of the same body, and partakers of the promise in Christ Jesus through the gospel. ... 9 and to make all men see what is the plan of the mystery hidden for ages in[a] God who created all things;