Does Paul's teaching in Ephesians 3 concerning "mystery" conflict with the Reformed confessions' view of the unity of the covenant of grace? The purpose of the author is to survey the meaning of the word "musterion" in secular and Jewish literature, including the Dead Sea Scrolls, and the writings of the Apostle Paul. He continues by relating the "mystery" teaching of Ephesians 3:5, 6 to the context of Paul's thought and of the whole Bible.