“For in [Christ] all the fullness of deity lives in bodily form, and you have been filled in him, who is the head over every ruler and authority.”
Christ’s physical fullness brings to his followers spiritual fullness. He is supreme. Nothing prevents him from filling his followers with his life.
How to realize this fullness? By developing our love for him and his people. By strengthen our hope in his coming. By growing in faith that all will be fulfilled in his time.