"But when anyone accepts what he has not seen, believing on the word of his teacher, the faith by which he honors the one his teacher proclaims to him is worthy of great praise. Blessed, therefore, is everyone who believes the message of the holy apostles who, as Luke says, were eyewitnesses of Christ's actions and ministers of the word. If we desire eternal life and long for a dwelling place in heaven, we must listen to them."
Cyril of Alexandria (AD ~444), On John 12, 22: PG 74, 729-736
Cyril, a brilliant theologian and major opponent of the Arian and Nestorian heresies, was the patriarch of Alexandria. He also presided over the council of Ephesus in 431, at which time the title of Mary as Theotokos, "the Mother of God," "the God-bearer," was solemnly recognized. Like so many official dogmatic statements the Church has made, this was merely a formal declaration of what the body of common believers had been believing and testifying to for centuries. It merely had to be expressed in a precise, binding manner in opposition to an heretical insurgency.