(1) The “mystery of faith†(1 Tim. 3:9). “The faith†is not only the body of doctrine that sets forth the heavenly truths revealed in Paul’s gospel, but that spiritual apprehension of them that held them fast in the spirit and in a good conscience. It is not opinions, but vital revelations of the Gospel, held as living oracles of God.
(2) The mystery of the union of Christ and the Church as His Body and Bride, is especially revealed in Eph. 5, but appears throughout all the Pauline epistles, even in Romans 12:5, as also in 1 Cor. 12:12, and Eph. 1:22, 23. This union is the basis of all the exhortations to love and obedience.
(3) The “mystery of Christ†(Eph. 3:4), shows that in this mystical Christ there is neither Jew nor Gentile, all having been chosen in Him before the foundation of the world, having been cut off from their connection by birth with the first Adam, at the Cross, and created anew in Christ. Paul was made minister of this mystery and given the task “to make all men see what is the stewardship of this mystery which for ages has been hid in God Who created all things†(Eph. 3:9). The object was that through this Church might be made known the manifold wisdom of God unto the principalities and powers in the heavenly places.
The Church itself was to belong to heaven, though formed by the Spirit on earth, Christ Himself being the Head of it, and every believer a member of Christ and of one another in this Body which will be (has been) given the highest place in glory, though recreated from earth’s sinners, according to “the purpose of the ages,†which the Father purposes in the Son. The highest place given to the lowest creatures, thus reveals the character of the Father  His manifold wisdom forever as nothing else could do. God is Himself love, and the Cross is an exhibition of that love and the commendation of it.
The Church, being given the highest position in heaven, will exhibit the activity of that love which is called in Scripture, grace. The world knows nothing of this. It regards the Church as having taken Israel’s place, and being simply an earthly religious organization seeking to obey the general human conscience. The world knows nothing of the fact that the Church is already called, justified, and glorified, being united to Christ Himself, in death, risen and seated with Him in the heavenly places; and that same favor is extended to it, that is extended to the Father’s Beloved, its Head; and its worship is by the Holy Spirit.
(4) The mystery of God  even Christ, “in whom are all the treasures of wisdom and knowledge hidden†(Col. 2:2, 3). This heavenly and glorified Lord Jesus is revealed to the heart of the believer as the Object of his worship, faith, praise and fellowship  by the Holy Spirit. This heavenly One is altogether unknown by the unsaved man.
(5) The mystery of Christ indwelling the believer (Col. 1:26, 27). He is called “Christ in you, the hope of glory.†“Abide in me, and I in you†(Col. 1:27; John 15:4). This is the great two-fold mystery, which in these Colossians verses is said to “fill up†the Word of God, being the highest revelation therein, and being the mystery which hath been hid from the ages and generations, but now being manifested. The “riches of the glory of this mystery†is made known to saints.
(6) The mystery of the Rapture of the Church at the Lord’s coming into the air, involving both the raising of those who have fallen asleep in the Lord Jesus, and also those alive at the moment (1 Thess. 4; 1 Cor. 15).
(7) The mystery of the fellow-heirship in Christ of Jew and Gentile (Eph. 3:3, 4, 9). This mystery does not seem great to us now who live on this earth, where we are accustomed to Jew and Gentile distinction as well as national differences generally, but when we remember that the Church was chosen in Christ before the foundation of the world (when there was no such distinction, or, indeed, any human being whatsoever), we see how great a secret this is: especially in view of the peculiar promises to national Israel in the Old Testament.
(8) The mystery of the wisdom of God, in secret in Christ: so that Paul and true preachers speak the wisdom of God that hath been hidden before the ages for our glory (1 Cor. 2:7). These things are revealed to us by the Spirit Who not only refuses to use man’s wisdom but also man’s words: “in words which the Spirit teacheth combining (or expressing) spiritual things with spiritual words.â€Â
(9) The mystery of the Kingdom of God, in righteousness, peace, and joy in the Spirit (Rom. 14:17). Only new-born or new-created men in Christ know this mystery ( 2 Cor. 5:17; John 3:3).
(10) The mystery of iniquity (2 Thess. 2:7). Satan is not permitted as yet to bring forth fully the “apostasy,†which will come when the world worships Satan intelligently (Rev. 13), the Church having been previously taken away according to 1 Thessalonians 4:13–18, and Revelation 3:10). Babylon or “confusion†is another name for this mystery in this age  see harlot church (Rev. 17), centered in seven-hilled Rome.
(11) The mystery of the hardening in part of Israel (Rom. 11:25). Though there is at present a remnant according to the election of grace, yet national Israel’s eyes are peculiarly blinded to their own Scriptures, to Christ as their Messiah, and to grace as God’s only method of salvation.
(12) The mystery of God’s will purposed in Christ, looking unto “a dispensation of the fullness of times, to sum up (Eph. 1:10) all things in Christ (that is). the things in the heavens and the things upon the earth†(not the lower or lost world, as in Phil. 2:10; Rev. 5:13). The foundation of this in Eph. 2:10, will be the ¬œBlood of His Cross†(Col. 1:19, 20). The saints alone have this mighty future purpose of God revealed to them; all others count upon man and the earth, which is cursed.  Wm. R. Newell