The passage that was explored this Sunday, Colossians 1:15-20, is credited with having a 'high' Christology. Jesus is the cosmic Christ in whom all things hold together: both creation and redemption. Contrast this with Gospels accounts of Jesus' temptation where he grows hungry, or his crucifixion where he can no longer carry the weight of his own cross. In these stories we witness the humanity of Jesus.
What the early church recognised was that we need to recognise both the humanity and divinity of Jesus. The Council of Chalcedon, the fourth ecumenical council of the early church, came up with this definition that recognises the two natures of Christ:
"Therefore, following the holy fathers, we all with one accord teach men to acknowledge one and the same Son, our Lord Jesus Christ, at once complete in Godhead and complete in manhood, truly God and truly man, consisting also of a reasonable soul and body; of one substance with the Father as regards his Godhead, and at the same time of one substance with us as regards his manhood; like us in all respects, apart from sin; as regards his Godhead, begotten of the Father before the ages, but yet as regards his manhood begotten, for us men and for our salvation, of Mary the Virgin, the God-bearer; one and the same Christ, Son, Lord, Only-begotten, recognized in two natures, without confusion, without change, without division, without separation; the distinction of natures being in no way annulled by the union, but rather the characteristics of each nature being preserved and coming together to form one person and subsistence, not as parted or separated into two persons, but one and the same Son and Only-begotten God the Word, Lord Jesus Christ; even as the prophets from earliest times spoke of him, and our Lord Jesus Christ himself taught us, and the creed of the fathers has handed down to us." (see the Council of Chalcedon at reformed.org).
When we forget Jesus' humanity we end up with a gnostic Jesus that doesn't have dirty feet. Maybe something like that which is taught in Scientology. When we forget Jesus' divinity we end up with someone who is little more than a prophet, something that the Jehovah's Witnesses teach. In either case the God made known is Jesus is marginalised and diminished.
Fourth century theologian, Gregory of Nanzianzus, said "That which He [Jesus] has not assumed He has not healed." Only in becoming human can Jesus save us, but he can only save us because he is God.