Une Minute avec Marie
Faire connaître et aimer Marie
Theotokos is the title that was officially attributed to Mary in the fifth century, to be exact, at the Council of Ephesus in 431, but which had already taken root in the devotion of the Christian people since the third century, in the context of the heated discussions on the Person of Christ in that period.
This title highlights the fact that Christ is God and truly was born of Mary as a man: in this way his unity as true God and true man is preserved. Actually, however much the debate might seem to focus on Mary, it essentially concerned the Son. Desiring to safeguard the full humanity of Jesus, several Fathers suggested a weaker term: instead of the title Theotokos, they suggested Christotokos, "Mother of Christ"; however, this was rightly seen as a threat to the doctrine of the full unity of Christ's divinity with his humanity.
On the one hand, therefore, after lengthy discussion at the Council of Ephesus in 431, as I said, the unity of the two natures—the divine and the human (cf. DS, n. 250)—in the Person of the Son of God was solemnly confirmed and, on the other, the legitimacy of the attribution of the title Theotokos, Mother of God, to the Virgin (ibid., n. 251).