I just thought I'd mention it, since Papa Benedict will be visiting Ephesus during his journey to Turkey. This trip of his can really teach us much about history. The Council, held in AD 431, debated the Nestorian heresy which was contested by Nestorius, Bishop of Constantinople (modern day Turkey) and St. Cyril, Patriarch of Alexandria. The heresy of Nestorius, according to the Catholic Encyclopedia, is not difficult to define,
|far as words are concerned: Mary did not bring forth the Godhead as such (true) nor the Word of God (false), but the organ, the temple of the Godhead. The man Jesus Christ is this temple, "the animated purple of the King", as he expresses it in a passage of sustained eloquence. The Incarnate God did not suffer nor die, but raised up from the dead him in whom He was incarnate. The Word and the Man are to be worshipped together, and he adds: dia ton phorounta ton phoroumenon sebo (Through Him that bears I worship Him Who is borne). If St. Paul speaks of the Lord of Glory being crucified, he means the man by "the Lord of Glory". There are two natures, he says, and one person; but the two natures are regularly spoken of as though they were two persons, and the sayings of Scripture about Christ are to be appropriated some of the Man, some to the Word. If Mary is called the Mother of God, she will be made into a goddess, and the Gentiles will be scandalized.|
As it turns out, Nestorius' doctrines meant well. He was reacting to the vagueness and at times heterodoxy of Christology as it was faintly understood back then. But we note how even an eloquent theologian and bishop can get things wrong, no matter how well meaning. It's a daunting responsibility, being an apostle/bishop, and one hopes that such a one has really got the charism of teaching, wisdom, knowledge, and the true ordination of episcopal authority. The consequences are too awful to contemplate.