Ephesians 3:19

And to know the love of Christ which passeth knowledge, that ye may be filled with all the fullness of God.

"The love of Christ" being made here the object of the verb "know" indicates quite clearly that "the love of Christ" is not primarily the thing under consideration in the previous verse, despite the fact of the vast majority of scholars taking exactly that position. As Blaikie said:

When "the love of Christ" is made the subject of a separate part of the prayer, and is not in the genitive, but in the objective case, governed by a verb of its own, this explanation is not to be entertained.[42]

That ye may be filled with all the fullness of God ... This is the grand climax of a prayer which reaches the most exalted heights. Paul here prayed for the Christians to whom he wrote that they might be filled with "all the fullness of God." No wonder this has been called the boldest prayer ever prayed. Dummelow was doubtless correct in interpreting this to mean: "That ye may be filled up to all the fullness of God, to the perfection of the divine attributes (Matthew 5:48).[43] See discussion of "Perfection of Christians" under Ephesians 1:4.

[42] W. G. Blaikie, op. cit., p. 108.

[43] J. R. Dummelow, op. cit., p. 963.