To know the love of Christ, which passeth knowledge. — The intentional paradox of this expression is weakened if (with many interpretations) we suppose that there is opposition in kind between knowledge referred to in the two clauses: as if “to know” meant to know by faith and spiritual experience, while the “knowledge,” which the love of Christ “passes,” is mere “human knowledge” — head-knowledge, and the like. Of such opposition there is no trace (contrast 1 Corinthians 2:6-16). In the original, the word “to know” is in a tense which expresses cognition in a particular case; hence the meaning of St. Paul’s prayer seems to be that they may know from time to time, as each opportunity offers, what must in its entirety pass all human knowledge, either to discover or fully to understand, even when revealing itself; so that they may always go on from faith to faith, from knowledge to knowledge, and yet find new depths still to be fathomed. The “love of Christ” is the love which He bears to us, and which is the motive of His sacrifice for our redemption. It is known only by those who are rooted in love to Him; such love being at once the consequence of the first knowledge of His love to us (1 John 4:19) and the condition of entering more deeply into that knowledge.
That ye might be filled with (or, rather, up to) all the fulness of God. — This clause must be taken as dependent, not merely on the clause immediately preceding, but on the whole sentence. It describes the final and glorious consequence of the indwelling of Christ in the heart, viz., the “being filled” with grace “up to the fulness of God.” The meaning is more clearly seen in the fuller expression below (Ephesians 4:13): “till we all come... to the measure of the stature of the fulness of Christ.” It is simply perfect conformation to the image of Him in whom “dwells all the fulness of the Godhead bodily” (Colossians 2:9), and whose fulness is therefore the “fulness of God,” manifesting all the attributes of the divine nature. The process is described in 2 Corinthians 3:18, “We all, with open face beholding as in a glass the glory of the Lord, are changed into the same image from glory to glory;” its consummation in 1 John 3:2, “When He shall appear, we shall be like Him; for we shall see Him as He is.” (Comp. Philippians 3:20-21.) Here it completes the climax. When Christ dwells in the heart we have first, love perfecting the faith which roots the life in Him; next, a thoughtful knowledge, entering by degrees into the unsearchable riches of His love to us; and, lastly, the filling the soul, itself weak and empty, up to the perfection of likeness to Him, so renewing and deepening through all time and eternity the image of God in our humanity.