What does it mean that Christ is the image of the invisible God?
Christ as the image of the invisible God means He is the likeness, physical appearance, and visible manifestation of God. God, who is invisible, is made visible in Christ in flesh and bodily form. The Son displays the likeness of the unseen God.
Les explains that verse 15 is speaking of the Son mentioned in verse 13, and He is the image—the likeness, physical appearance—of the invisible God. That is what Christ is. He is the visible manifestation in the flesh, bodily, of the invisible God. In other words, the Son makes the unseen God visible in bodily form.