Following intense arguments with Nestor, Cyril of Alexandria proposed the following 12 rules of which if any where broken, the individual would be anathematised, meaning formally set apart from the church, ie excommunicated.
The council of Ephesus endorsed these rules and they are mentioned below.
1. If anyone does not confess that Emmanuel is God in truth, and therefore that the holy virgin is the mother of God (for she bore in a fleshly way the Word of God become flesh, let him be anathema.
2. If anyone does not confess that the Word from God the Father has been united by hypostasis with the flesh and is one Christ with his own flesh, and is therefore God and man together, let him be anathema.
3. If anyone divides in the one Christ the hypostases after the union, joining them only by a conjunction of dignity or authority or power, and not rather by a coming together in a union by nature, let him be anathema.
4. If anyone distributes between the two persons or hypostases the expressions used either in the gospels or in the apostolic writings, whether they are used by the holy writers of Christ or by him about himself, and ascribes some to him as to a man, thought of separately from the Word from God, and others, as befitting God, to him as to the Word from God the Father, let him be anathema.
5. If anyone dares to say that Christ was a God-bearing man and not rather God in truth, being by nature one Son, even as “the Word became flesh”, and is made partaker of blood and flesh precisely like us, let him be anathema.
6. If anyone says that the Word from God the Father was the God or master of Christ, and does not rather confess the same both God and man, the Word having become flesh, according to the scriptures, let him be anathema.
7. If anyone says that as man Jesus was activated by the Word of God and was clothed with the glory of the Only-begotten, as a being separate from him, let him be anathema.
8. If anyone dares to say that the man who was assumed ought to be worshipped and glorified together with the divine Word and be called God along with him, while being separate from him, (for the addition of “with” must always compel us to think in this way), and will not rather worship Emmanuel with one veneration and send up to him one doxology, even as “the Word became flesh”, let him be anathema.
9. If anyone says that the one Lord Jesus Christ was glorified by the Spirit, as making use of an alien power that worked through him and as having received from him the power to master unclean spirits and to work divine wonders among people, and does not rather say that it was his own proper Spirit through whom he worked the divine wonders, let him be anathema.
10. The divine scripture says Christ became “the high priest and apostle of our confession”; he offered himself to God the Father in an odour of sweetness for our sake. If anyone, therefore, says that it was not the very Word from God who became our high priest and apostle, when he became flesh and a man like us, but as it were another who was separate from him, in particular a man from a woman, or if anyone says that he offered the sacrifice also for himself and not rather for us alone (for he who knew no sin needed no offering), let him be anathema.
11. If anyone does not confess that the flesh of the Lord is life-giving and belongs to the Word from God the Father, but maintains that it belongs to another besides him, united with him in dignity or as enjoying a mere divine indwelling, and is not rather life-giving, as we said, since it became the flesh belonging to the Word who has power to bring all things to life, let him be anathema.
12. If anyone does not confess that the Word of God suffered in the flesh and was crucified in the flesh and tasted death in the flesh and became the first born of the dead, although as God he is life and life-giving, let him be anathema.