This takes direct revelation from God, as revealed to Peter, and the final and finished revelation of the mystery to Paul. Matthew 16:16-18 And Simon Peter answered and said, Thou art the Christ, the Son of the living God. And Jesus answered and said unto him, Blessed art thou, Simon Barjona: for flesh and blood hath not revealed it unto thee, but my Father which is in heaven. And I say also unto thee, That thou art Peter, and upon this rock (revelation of Christ in you) I will build my church; and the gates of hell shall not prevail against it.
Colossians 1:25-28 Whereof I am made a minister, according to the dispensation of God which is given to me for you, to fulfil the word of God; Even the mystery which hath been hid from ages and from generations, but now is made manifest to his saints: 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: Whom we preach, warning every man, and teaching every man in all wisdom; that we may present every man perfect in Christ Jesus:
The mystery is to fulfill the Word of God. The mystery was hidden from the beginning of time.
The mystery is "Christ in you the Hope of Glory.
God had it planned before the foundation of the world. Ephesians 1:3-4 Blessed be the God and Father of our Lord Jesus Christ, who hath blessed us with all spiritual blessings in heavenly places in Christ: According as he hath chosen us in Him before the foundation of the world, that we should be holy and without blame before Him in love:
Those that are "In Christ", that is born again of incorruptable Seed have been baptized into Christ, seated in heavenly places in Christ Jesus. In Spirit saved, in soul/mind being saved and quickened in Body to be saved.
2Cr 1:10 Who delivered us from so great a death, and doth deliver: in whom we trust that he will yet deliver [us];
Who delivered us? The Spirit of Christ rebirthed in you the "Hope of Glory". Who is delivering us in our mind, It is the Mind of Christ that the Holy Spirit teaches us about in all we say or do. Who will deliver us? God the Father when these mortal bodies that have been quickened by the Incorruptable Seed of Christ are planted in the ground as Christ was and bring forth the Glory of the Lord and these bodies raised incorruptable unto the Father. Or changed in the twinkling of an eye at the rapture.
1 Peter 1:18-23 Forasmuch as ye know that ye were not redeemed with corruptible things, as silver and gold, from your vain conversation received by tradition from your fathers; But with the precious blood of Christ, as of a lamb without blemish and without spot: Who verily was foreordained before the foundation of the world, but was manifest in these last times for you, Who by Him do believe in God, that raised Him up from the dead, and gave Him glory; that your faith and hope might be in God. Seeing ye have purified your souls in obeying the truth through the Spirit unto unfeigned love of the brethren, see that ye love one another with a pure heart fervently: Being born again, not of corruptible seed, but of incorruptible, by the Word of God, which liveth and abideth for ever.
Born Again by the Word of God. Who is the Word.
John 1:1-4 In the beginning was the Word, and the Word was with God, and the Word was God. The same was in the beginning with God. All things were made by Him; and without Him was not any thing made that was made. In Him was life; and the life was the light of men.
Again; "Christ in you the Hope of Glory", this is the mystery.
Rom 8:11 But if the Spirit of him that raised up Jesus from the dead dwell in you, he that raised up Christ from the dead shall also quicken your mortal bodies by His Spirit that dwelleth in you.
1Cr 15:36 [Thou] fool, that which thou sowest is not quickened, except it die:
Eph 2:1 And you [hath he quickened], who were dead in trespasses and sins;
Eph 2:5 Even when we were dead in sins, hath quickened us together with Christ, (by grace ye are saved;)
Col 2:13 And you, being dead in your sins and the uncircumcision of your flesh, hath He quickened together with Him, having forgiven you all trespasses;
1Pe 3:18 For Christ also hath once suffered for sins, the just for the unjust, that He might bring us to God, being put to death in the flesh, but quickened by the Spirit:
In Christ: Phillip