Conciliar Teaching for The Day

Theotokos, from Hagia Sophia, (now a mosque)

From the Council of Ephesus (431 AD), defining the doctrine of the Virgin Mary as Theotokos, or Mother of God, courtesy of New Advent, full text here:

If anyone will not confess that the Emmanuel is very God, and that therefore the Holy Virgin is the Mother of God (Θεοτόκος), inasmuch as in the flesh she bore the Word of God made flesh [as it is written, The Word was made flesh] let him be anathema.