There is an objective faith, by which we were saved, and also there is subjective or personal faith; both are at work in the Christian believer's life of faith. Here we will address subjective or personal faith.

Paul says he had received personal "Revelation of The Mystery" directly from the Lord Jesus Christ.

Ephesians 3:3 How that by REVELATION he (Christ) made known unto me (Paul) THE MYSTERY; (as I wrote afore in few words,

What was this personal revelation Paul received? It was of "Christ IN Paul," as He is in ALL believers.

Gal 1:15-16 But WHEN IT PLEASED GOD, who separated me from my mother's womb, and called me by his grace, 16 To REVEAL His Son In Me, that I might preach him among the heathen (Gentiles)...

The core of "the Mystery" that Paul received and preached is clearly seen in these verses.

Col 1:25-27 I (Paul) am made a minister, according to the dispensation of God which is given to me for you, to fulfil the word of God; 26 Even (that is) THE MYSTERY which hath been hid (concealed) from ages and from generations, but now is made manifest (revealed) to his saints: 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:

Revelation such as Paul's is the normal necessary supernatural work of the Holy Spirit in the life of every believer. Personal REVELATION is what Paul prayed for the Ephesians (see below) because REVELATION is key to one experiencing leaps of subjective or personal faith as major stepping stones in the Lord. What we see by REVELATION becomes ours... then being permanently imprinted in our soul's mind's eye!

Ephesians 1:16-18  (I Paul) Cease not to give thanks for you, making mention of you in my prayers; 17 That the God of our Lord Jesus Christ, the Father of glory, may Give Unto You THE SPIRIT OF WISDOM AND REVELATION In The Knowledge (ginosko, Experiential Knowledge) OF HIM (Christ): 18 The eyes of your understanding being enlightened; that ye may know what is the hope of his calling, and what the riches of the glory of his inheritance IN the saints (the believers),

The only Christ we can personally come to know is the Christ who indwells us. This thought then this leads us to the need for the "Revelation Of The Mystery." Note in the verses above that the purpose for the REVELATION that Paul prayed for the Ephesians was not so that they would have power, peace, or other attributes of Christ, but rather for the experiential knowledge of Christ Himself who actually is all of those attributes within us already as believers.

Paul says it is seeing "Christ according to The Revelation Of The Mystery" that is able to ground and establish believers.

Romans 16:25 Now to him that is of Power To Stablish You according to my (Paul's) gospel, and the preaching of Jesus Christ, According To The Revelation Of The Mystery, which was kept secret since the world began,

"Paul, THE Apostle to the Gentiles," (Rom 11:13) says he preached the "unsearchable riches of Christ," referring to what he came to see and receive by REVELATION.

Ephes. 3:8 Unto me, who am less than the least of all saints, is this grace given, that I should preach among the Gentiles the unsearchable riches of Christ;"

Paul went onto the next verse to speak of "the Fellowship Of The Mystery."

Ephes. 3:9 And to make all men see what is the Fellowship of the Mystery, which From The Beginning Of The World Hath Been Hid In God, who created all things by Jesus Christ:

Paul tells us "The Mystery" or secret plan of God is "CHRIST IN YOU The Hope Of Glory" (Col 1:27). It is by Christ indwelling us that we have union or fellowship with Christ in all our living, day by day, moment by moment. He is present, perhaps in the background much of the time, in all that we do; we have the inner sense of His life within us to guide, direct, and sometimes restrain us.

So Paul saw the "fellowship (Gk., koinonia) of the Mystery" of Christ in the believers, which he preached "among the Gentiles." He preached the "unsearchable riches of Christ" in the believer. The word "fellowship" in the phrase "Fellowship of the Mystery" is the Greek "koinonia," which may be translated "fellowship or communion." Every believer possesses "the unsearchable riches of Christ" within them by His "Spirit of life" in union with their spirit such that we are now "one spirit" (1Cor 6:17) with Him.

This was Paul's message; "the mystery, which is Christ in you ...28 whom we preach" (Col 1:27b-23a). The believer can enjoy the literal union of "the Spirit of life in Christ Jesus" (Rom 8:2a) within their human spirit (cf., John 3:6), where they are literally and eternally "one spirit" with Christ.

As seen by its Greek word is "anexichniastos," the word " unsearchable" would be a better translated " untraceable " (above). The limitless riches of the resurrected Christ had never been revealed and traced out before Paul received knowledge of them from the ascended Lord Jesus..."by revelation."

Some might ask, why hadn't these truths of the mystery been traced out before Paul, perhaps by Peter, James, or John? Its because these truths could not have been known until they were first revealed by the ascended Lord Jesus Christ to "Paul, the Apostle to the Gentiles." It was given to Paul to bring this "Revelation Of The Mystery" of God's secret gospel, the message of "the gospel of the grace God"… for the Gentiles.

Ephes. 3:2-3 If ye have heard of the dispensation (administration) of the grace of God which is given me (Paul) to youward (the members of the body of Christ): 3How that By Revelation He Made Known Unto Me (Paul) The Mystery; (as I wrote afore in few words,

Paul was to administer or dispense these truths to the new found members of the church called "the body of Christ." Paul dared to call this message of the pure grace of God for the Gentiles "my gospel" because Christ gave it to Paul specifically to preach to the Gentiles. The word "Mystery," is from the Greek "musterion," actually meaning "a secret" - in this case it was a "secret" that was held by God "from before  the foundation of the world" (Eph 1:4). Paul says this "Mystery" gospel for the Gentiles had been "Kept Secret Since The World Began" (below). It was not known to the Patriachs or prophets of the OT.

Romans 16:25  Now to him that is of power to stablish you according to my gospel, and the preaching of Jesus Christ, according to THE REVELATION OF THE MYSTERY, which Was KEPT SECRET SINCE THE WORLD BEGAN,

Gentiles were considered as dog and "strangers from the covenants of promise, without hope and without God in the world" (Eph 2:12). But the secret revealed to Paul was that "the Spirit of life in Christ Jesus" would come to dwell in (abide within) the human spirit of believing Gentiles, to be their new and eternal life... just as God has promised to do also in the believers of Israel when they ultimately receive their Messiah (cf., Ezekiel 37:14). This He will do at His 2nd coming to earth to set up the Millennial kingdom on earth, when Israel looks "upon Him who they have pierced" (Zech 12:10).

Jesus of Nazareth obviously knew "the Mystery" but didn't reveal "the Mystery" concerning His Spirit ultimately coming to indwell of the Gentile believers. Gentiles who had heretofore been "without God, and without hope in the world" (Eph 2:12), now had "the hope of (eternal) glory." With that they gained the eternal life, which is the glory expression of the eternal Godhead, by Christ in their spirits.

Col. 1:26-27 Even THE Mystery which hath been hid from ages and from generations, but now is made manifest to his saints: 27To 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:

Every believer MUST come to a "the Revelation of The Mystery" of Christ indwelling them in order for them to become an intimate KNOWER of Christ and of the truths of Paul's gospel based upon "the Mystery" of His indwelling "Spirit of life in Christ Jesus."

Upon coming to such Revelation and knowledge a believer's life is therewith revolutionized. Not only is their Bible refreshed anew, they also then have come to a more secure relationship with God by seeing they NOW have an intimate union with Christ and all that He is within them. They then know He, with His life and nature within them, is their all-sufficiency now and forever!