Ephesians 3:19

To know [γ ν ω ν α ι]. Practically, through experience; while apprehend marks the knowledge as conception.

Love of Christ. Christ's love to us. Human love to Christ could not be described in these terms.

Which passeth knowledge [τ η ν υ π ε ρ β α λ λ ο υ σ α ν τ η ς γ ν ω σ ε ω ς].

Which surpasses mere knowledge without the experience of love. Note the play on the words know and knowledge.

That ye might be filled with all the fullness of God [ι ν α π λ η ρ ω θ η τ ε ε ι ς π α ν τ ο π λ η ρ ω μ α τ ο υ θ ε ο υ]. Note the recurrence of that; that He would grant you; that ye may be strong; that ye may be filled. With is better rendered unto, to the measure or standard of. Fullness of God is the fullness which God imparts through the dwelling of Christ in the heart; Christ, in whom the Father was pleased that all the fullness should dwell (Colossians 1:19), and in whom dwelleth all the fullness of the Godhead (Colossians 2:9).