Through whom did God share the secret kept hidden?
God shared the secret kept hidden through the Apostle Paul. The context states He is now seen fit by His grace to release these things kept secret, sharing them with us through the Apostle Paul. This secret concerns God, the Father, and Christ, in whom are hid all treasures of wisdom and knowledge.
Les teaches that the secret of God, the Father, and of Christ, in whom are hid all the treasures of wisdom and knowledge, had been kept secret. But now God is seen fit by His grace to release these things kept secret, and He is sharing them with us through the Apostle Paul. Les contrasts this with Jesus, who did not reveal the mysteries, and Peter, who did not have the mysteries. Paul says in 2 Corinthians 11:5 that he was not a whit behind the very chiefest apostles, not a step behind Peter in authority, but up there a little bit ahead. Paul also says he is more a minister of Christ than those who were Hebrews, Israelites, the seed of Abraham, and ministers of Christ.