Paul had never met the Colossian Christians; he nevertheless sought to strengthen them in their faith and assurance in Jesus. Jesus is the treasure of all knowledge and wisdom; we have no need to look elsewhere.
Now I rejoice in my sufferings for your sake, and fill up on my part that which is lacking of the afflictions of Christ in my flesh for his body’s sake, which is the church; whereof I was made a minister, according to the dispensation of God which was given me to you-ward, to fulfil the word of God, even the mystery which hath been hid for ages and generations: but now hath it been manifested to his saints, to whom God was pleased to 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 proclaim, admonishing every man and teaching every man in all wisdom, that we may present every man perfect in Christ; whereunto I labor also, striving according to his working, which worketh in me mightily.
For I would have you know how greatly I strive for you, and for them at Laodicea, and for as many as have not seen my face in the flesh; that their hearts may be comforted, they being knit together in love, and unto all riches of the full assurance of understanding, that they may know the mystery of God, even Christ, in whom are all the treasures of wisdom and knowledge hidden. This I say, that no one may delude you with persuasiveness of speech. For though I am absent in the flesh, yet am I with you in the spirit, joying and beholding your order, and the stedfastness of your faith in Christ.
As therefore ye received Christ Jesus the Lord, so walk in him, rooted and builded up in him, and established in your faith, even as ye were taught, abounding in thanksgiving (Colossians 1:24-2:7).