KJV Galatians 2:20
20 I am crucified with Christ: nevertheless I live; yet not I, but Christ liveth in me: and the life which I now live in the flesh I live by the faith of the Son of God, who loved me, and gave himself for me.
The finishing of the mystery of God is the ending of the work of the gospel. And the end of the work of the gospel is first, the removal of all vestige of sin and the bringing in of everlasting righteousness... That is, Christ fully formed in the life of every believer...
KJV Colossians 1:27
27 To whom God would make known what is the riches of the glory of this mystery among the Gentiles; which is Christ in you, the hope of glory:
See also...
KJV Galatians 5:24
24 And they that are Christ's have crucified the flesh with the affections and lusts.
KJV Galatians 6:14
14 But God forbid that I should glory, save in the cross of our Lord Jesus Christ, by whom the world is crucified unto me, and I unto the world.
KJV Romans 6:4-6
4 Therefore we are buried with him by baptism into death: that like as Christ was raised up from the dead by the glory of the Father, even so we also should walk in newness of life.
5 For if we have been planted together in the likeness of his death, we shall be also in the likeness of his resurrection:
6 Knowing this, that our old man is crucified with him, that the body of sin might be destroyed, that henceforth we should not serve sin.
KJV Romans 8:3-4
3 For what the law could not do, in that it was weak through the flesh, God sending his own Son in the likeness of sinful flesh, and for sin, condemned sin in the flesh:
4 That the righteousness of the law might be fulfilled in us, who walk not after the flesh, but after the Spirit.
KJV Colossians 2:11-14
11 In whom also ye are circumcised with the circumcision made without hands, in putting off the body of the sins of the flesh by the circumcision of Christ:
12 Buried with him in baptism, wherein also ye are risen with him through the faith of the operation of God, who hath raised him from the dead.
13 And you, being dead in your sins and the uncircumcision of your flesh, hath he quickened together with him, having forgiven you all trespasses;
14 Blotting out the handwriting of ordinances that was against us, which was contrary to us, and took it out of the way, nailing it to his cross;
KJV Romans 6:8, 13
8 Now if we be dead with Christ, we believe that we shall also live with him:
13 Neither yield ye your members as instruments of unrighteousness unto sin: but yield yourselves unto God, as those that are alive from the dead, and your members as instruments of righteousness unto God.
KJV 1 Timothy 3:16
16 And without controversy great is the mystery of godliness: God was manifest in the flesh, justified in the Spirit, seen of angels, preached unto the Gentiles, believed on in the world, received up into glory....
.... The gospel.