The title of "Mother of God" (Theotokos) was confirmed by the first Council of Ephesus, held at the church of Mary in the year 431 C.E. - The Council decreed that Mary is the Mother of God because her son Jesus is one person, who is both God and man, human and divine. Therefore, the church rightly celebrates this great feast at the beginning of each calendar year.  The biblical readings assigned to this solemnity highlight some reasons to celebrate the Mother of God. First. Eve brought us death, Mary brought us life.  Second, Mary is integral part of our salvation history. Third, Christmas is the most powerful reason why Mary is the Mother of God.