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There is also a special concept that is typical of these two letters, and it is the concept of "mystery." Once the "mystery of the will" of God is spoken of (Ephesians 1:9) and other times, the "mystery of Christ" (Ephesians 3:4; Colossians 4:3), or even the "mystery of God, Christ, in whom are hidden all the treasures of wisdom and knowledge" (Colossians 2:2-3).
This makes reference to the inscrutable divine design over the destiny of man, of peoples and of the world. With this language, the two epistles tell us that it is in Christ where the fulfillment of this mystery is found. If we are with Christ, even though we cannot intellectually understand everything, we know that we are in the nucleus and on the path of truth. He is in his totality, and not only one aspect of his person or one moment of his existence, he who gathers in himself the plenitude of the unsearchable divine plan of salvation.
In him takes shape what is called the "manifold wisdom of God" (Ephesians 3:10), since in him "dwells the whole fullness of the deity bodily" (Colossians 2:9). From now on, then, it is not possible to think of and adore the approval of God, his sovereign disposition, without confronting ourselves personally with Christ in person, in whom the "mystery" is incarnate and can be tangibly perceived. Thus one comes to contemplate "the inscrutable riches of Christ" (Ephesians 3:8), which is beyond all human understanding.
It is not that God has not left the mark of his passing, since Christ himself is the footprint of God, his maximum mark, but rather that one realizes "what is the breadth and length and height and depth" of this mystery "that surpasses knowledge" (Ephesians 3:18-19). Mere intellectual categories here prove insufficient, and recognizing that many things are beyond our rational capacities, we should trust in the humble and joyful contemplation, not just of the mind, but also of the heart. The fathers of the Church, on the other hand, tell us that love understands much more than reason alone.