“Meanwhile praying also for us, that God would open to us a door for the word, to speak the mystery of Christ, for which I am also in chains.”
“to speak the mystery of Christ”
“Mystery” does not mean something mysterious or spooky, but that which is known only to the initiated (Phil. 4:12, “I have learned the secret.”). The “mystery” was that which is known outside unassisted natural perception. In the New Testament, God made this information known by divine revelation. The “mystery” in this verse refers to the disclosure of the idea of the church. The concept of a church was not known in the Old Testament (Eph 3:1-13).
The English usage of “mystery” carries the idea of knowledge withheld. The biblical concept is that of truth revealed. Colossians 1:26 carries this sense, “The mystery which has been hidden from ages and generations, but now has been revealed to His saints.” The New Testament uses “mystery” of:
Truth revealed in the gospel (1 Cor. 13:2; 14:2).
Of Christ, who is God Himself incarnate (Col. 2:2; 4:3) and submitting himself to death (1 Cor. 2:1) and raised from the dead (1 Tim. 3:16), and the universe will be subject to him (Eph. 1:9) and is declared in the gospel (Rom. 16:25; Eph. 6:19).
Of the church, which is Christ’s body (Eph 5:32, the union of redeemed men with God in Christ).
Rapture of believers into the presence of Christ (1 Cor. 15:51).
The hidden forces that retard or accelerate the Kingdom of Heaven (Mt. 13:11; Mk 4:11).
The present condition of Israel (Rom. 11:25).
The spirit of disobedience to God (2 Thes. 2:7; Rev. 17:5,7; cp. Eph. 2:2).
The seven local churches and their messengers saw in symbol (Rev. 1:20).
The way of God in grace (Eph. 3:9). A comprehensive way (1 Cor. 4:1).
The secular Greeks used this term for their religious rites and ceremonies in their secret societies. Those initiated into these societies possessed specific special knowledge.
God did not reveal the idea of the church until the New Testament with all of its operating assets.
The mystery in our verse pertains to the church, which God did not reveal in the Old Testament. The Holy Spirit baptized no one in the Old Testament into the body of Christ (church). The Holy Spirit did not permanently indwell all believers in the Old Testament. He did indwell a few, such as Samson and David. On the other hand, every believer in the church is a full-time priest.