AnswerA series of Councils of bishops gradually formulated much of Christian doctrine over the centuries. The most famous of these was the Council of Nicaea, called by the Roman emperor Constantine.

In some cases, important new doctrines were adopted in Western Chritianity, but not in the East. For example, the concept of the Trinity was adopted after the Council of Nicaea, and thus accepted by both branches of the central Christian Church. The Filioque clause, which holds that the Father and the Son are equally divine, was subsequently adopted in the West, but Orthodox Christianity holds that this is not true, calling it a "novelty and augmentation of the Creed", even a heresy. The Protestant Churches have their own views on what constitutes true doctrine. In the case of the Filioque, the Anglican Church considered omitting the Filioque from the Nicene Creed, but has not followed through with a definitive decision.