incarnation continued

Key idea
But the key idea was set out in that first sentence, "In the beginning was the Word." John was affirming and underlining one of the essentials of the Incarnation, the eternal pre-existence of the Divine Son.
This simply means that the Word, the Son or second Person of the Holy Trinity, always is. He has no beginning or end. He is God from all eternity, one and equal with the Father and the Holy Spirit. As Catholics we may take this for granted, because it is the Church's own understanding of John's language. However, once we explore heresies that have denied or redefined the Incarnation, we find that Christianity in the 21st century faces errors about the Incarnation as did the era of Saint John in the late first century.
Under pagan Greek influences, gnostic heretics simply denied that God assumed a real human nature and a body that could suffer. Jesus only seemed human. This is known as Docetism. But other, more plausible and more rational, heresies moved in the opposite direction. They struck not at the humanity of Christ but at his divinity, especially by reinterpreting Saint John's affirmation of the eternal pre-existence and divinity of the Son of God who took flesh.