Within the church at Colossae, there was a desire for “fullness”. So, to gain fullness, they placed alongside Jesus dietary rules, religious festivals, the worship of angels, false humility, philosophy etc.   With that in mind, Paul wants the Colossians to know for sure that all the fullness of God was pleased to dwell in Jesus and that we have been given fullness in him. And making that point, Paul gave the Colossians and us a magnificent vision of the Supremacy of Jesus: 

“We look at this Son and see the God who cannot be seen. We look at this Son and see God’s original purpose in everything created. For everything, absolutely everything, above and below, visible and invisible, rank after rank after rank of angels—everything got started in him and finds its purpose in him. He was there before any of it came into existence and holds it all together right up to this moment. And when it comes to the church, he organizes and holds it together, like a head does a body. He was supreme in the beginning and—leading the resurrection parade—he is supreme in the end. From beginning to end he’s there, towering far above everything, everyone. So spacious is he, so expansive, that everything of God finds its proper place in him without crowding. Not only that, but all the broken and dislocated pieces of the universe—people and things, animals and atoms—get properly fixed and fit together in vibrant harmonies, all because of his death, his blood that poured down from the cross.”  (Colossians 1:15 -20  The Message).

Here Paul shows us that there is nothing bigger or beyond  Jesus.  So we never seek fullness in Jesus plus something else. If we treat Jesus as merely a part of the picture, we become disconnected from him and then we no longer enjoy the fullness that is in him and only in him.