Complex sentence: From the West, Pope Damasus I and others defended Mary against Monophysitism, the teaching that Christ had only a divine nature; meaning that Mary is only the Mother of God, not the mother of the human Jesus.
Split into simpler sentences: From the West, Pope Damasus I and others defended Mary against Monophysitism, the teaching that Christ had only a divine nature. Accordingly, Mary is only the Mother of God, not the mother of the human Jesus.