Remembering our context (the battle is over syncretism) chapter one lays out the issue in profoundly clear terms. After offering a prayer of thanksgiving for the Colossians, Paul lays out the central theme in 1:15-20.
1. He is the image of the invisible God (John 1:14 -- . . . we have seen his glory, the glory as of a father's only son, full of grace and truth.") Jesus Christ is the human face of God.
2. First born of all creation -- again see John 1:1-5 -- Born is the key word here. Jesus is the only begotten Son of God -- begotten not made (created) -- as such the ancient ones believed that Jesus was of the same stuff God is and therefore God (one of the basis of the doctrine of the trinity)
3. in him all tings . . . were created. Christians believe that creation was an act of will and that God spoke the word and it was so (seen Genesis 1). Jesus is identified in John 1 as the "logos (word) of God". Therefore Christians believe that God the Creator performed creation through Christ the Son.
4. He is the head of the body the Church. Human institutional baggage aside, the Christian faith is not headed up by humans but by the resurrected Christ.
5. "For in him all the fulness of God was pleased to dwell (19)". This would be a great verse to simply contemplate and meditate on for a few moments (hours, days, weeks, months). What are the implications of "the fullness of God" dwelling in the human being Jesus? This is incarnation in its simplest form. The word became flesh and dwelt among us -- in him the fullness of God was pleased to dwell . . .
6. Through Jesus Christ comes salvation. Through Christ God has reconciled the world to himself. All humans have been reconciled we just need to live into the new reality -- accept what has already been done for us. We could live in rebellion (I'm not sure how that works out over time and eternity). But grace and peace and love and mercy and salvation are already extended (the Kingdom of the Heavens is among us!).
Because of all of this we don't need angels or saints or any intermediary to lead us into the knowledge of God or into a reconciled relationship with God. We are in direct relationship with God through his one and only begotten Son, Jesus Christ.