Thus the first thought in these words is that the Lord Jesus Christ, as Son of God and God, Himself knows all things. This greatly serves the Apostle's purpose, for it suggests: "If so, then everything must be asked of Him. He gives wisdom and knowledge" (Saint Chrysostom).
Yet, according to the flow of speech, another thought also seems possible in the Apostle. In the knowledge of the Lord and Savior there is all wisdom and all knowledge. Whoever knows Him as Savior acquires in that very knowledge all wisdom and all knowledge.
The knowledge of the Lord as Savior is the knowledge of the divine economy of our salvation in Him and through Him. This is the same as the knowledge of the mystery of God, mentioned just before.
In that case, "in whom," εν ω, must be recognized as referring to "mystery," μυστηριου. Then εν ω should be translated "in which," which Greek allows.
The Apostle's thought would be this. In the knowledge of the mystery of salvation in the Lord Jesus Christ there is all wisdom and all knowledge, or all rational understanding.
By this he suggested that nothing should be valued so highly, and nothing sought so earnestly, as the knowledge of this mystery. When you know it, then even if you know nothing else, you are wise, rational, and all-knowing.
Therefore, if someone approaches you as a wise man and begins to offer you a wisdom not in agreement with the knowledge of God's mystery in Christ Jesus, do not listen to him. He offers you not wisdom, but absurd speculation.
Ambrosiaster understands these words in this sense: "The Apostle desires that the Colossians know the mystery of God in Christ. They are to be persuaded that in it lies all the wealth of wisdom and knowledge, so as to confess Christ worshipfully in the fullness of the Godhead.
"In Christ is the whole hidden mystery of God. He is the one Savior. If any human flesh does not put its hope in Him, it will perish. Whoever knows Him will also have true knowledge of everything.
"Therefore it is rightly said that in Him are hidden all the treasures of wisdom and knowledge. Whoever knows Him needs nothing further in order to be acknowledged as wise and understanding, since he knows Him in whom all wisdom abides.
"Whatever knowledge anyone thinks he may find anywhere, he will find it richly in Him. For unbelievers it is incomprehensible how all wisdom and all knowledge are in Christ. They do not read astrology in the Gospel, geometry in the Apostle, or arithmetic and music in the Prophets.
"Our people do not pursue these things because they do not belong to salvation. Rather, they lead into error and away from God. Occupying themselves with these things and with the subtleties of their reasonings, men forget to care for the soul.
"What wisdom is more certain and true than to recognize what is saving, and to turn away from what is destructive? Destructive is whatever prevents the soul from caring for its salvation.
"Therefore it is not unjust to affirm that whoever has known Christ has found the treasure of wisdom and knowledge. For he has known what is saving for him."