Ephesians 1:23 - God's plan A

"...which is the body of Him, the fullness of the [One] the all in all filling."

-Christ is indeed over all things, and that includes those who have trusted in Him for salvation.  In fact, Paul says He is the Head of the Church, the gathered global Assembly of the people of God, which is the Body of Christ, and He is in charge.  He is in control.  He sets direction and make the decisions.

-This Body is the fullness of this One Who fills up all things with all things.  In other words, this Body is the ultimate expression of what God’s filling up looks like.  You could say that were you able to completely remove the presence and activity of God, His goodness, His sustaining and upholding power, His grace and provision, you would be left with nothing.  Disorder and chaos would ensue, randomness, anarchy, evil, and ultimately death and destruction, as the very particles of matter themselves would fly apart.  But in all the created universe, we find in this Body of Christ the finest and fullest expression of what it looks like for God to completely fill to overflowing, His presence, His goodness, His power and love, His peace and joy.  This is the pinnacle of God’s creation, men and women fully surrendered and freely choosing to love Him with all their hearts and to love one another and their neighbors with all the love of God, come what may, laying down their interests and their lives for others, even unto death.  This is life at its fullest, life as it was always intended to be.  This was His plan from the beginning.

-Another way of looking at this metaphor of the Assembly of believers being the body of Christ is that they become the primary means of locomoting His life to the ends of the earth, of disseminating the blessings of God to the nations.  this living, moving, breathing spiritual mass are the hands and feet of Jesus to men, women, and children everywhere, guided and animated by Him Who is the Head.  The Church is God's plan A for bringing the peoples of the earth into contact with His glory, into the white-hot enjoyment of His breathtaking greatness and goodness.  When He declares that all the earth will be filled with His glory (Numbers 14.21) - this is how He intends to do it, as God is most glorified when His people are finding their highest satisfaction in Him, in all things, whatever they do, wherever they go (1Corinthians 10.31).