In the Old Testament, much of God’s plan was kept as a mystery, intentionally. Most of the New Testament speaks plainly because God is opening to all what was once hidden. He reveals for the very purpose of bringing clear understanding. “For we are not writing to you anything other than what you read and understand.” (2 Corinthians 1:13)
The mystery was made known to me by revelation, as I have written briefly. When you read this, you can perceive my insight into the mystery of Christ, 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. This mystery is that the Gentiles are fellow heirs, members of the same body, and partakers of the promise in Christ Jesus through the Gospel. (Ephesians 3:3-6 cf. Romans 16:25-26)
I became a minister… to make the word of God fully known, the mystery hidden for ages and generations but now revealed to His saints. To them God chose to make known how great among the Gentiles are the riches of the glory of this mystery, which is Christ in you, the hope of glory. (Colossians 1:25-27)
The mystery is Christ. He is the climax of God’s centuries of preparation. But this is not about some remote reality. This is “Christ in you!” Within you, He is “the hope of glory”—the assurance for your glorious future. This, too, is a major theme of the New Testament: This same Jesus is coming again in His full majesty for everyone to see (Acts 1:11; Revelation 1:7). He comes to judge the world (Matthew 25:31- 46; 2 Thessalonians 1:7-10). But for you who know Him, He comes to welcome you home (John 14:3; Hebrews 9:28).