Chalcedon insisted that Jesus is one with God and fully human and that he is both of these at the same time without separation or confusion. It did not realize that a literal virgin birth in fact introduces a confusion of the two. The birth of Jesus initiated by God without a human father but with a human mother confuses the categories of divine and human by identifying the divine aspect of Jesus with his conception in space and time and makes an exception to what was confessed about his full humanity. It replaces an aspect of normal human existence for Jesus with a divine property.
