2.23 What were the main Church Councils?
All Church Councils are aimed at achieving a more in-depth understanding of the faith, not at changing it. One result of the first two councils, which were held in 325 and 381 AD, was the Creed, the profession of the faith. You can find the Creed in many languages in the #TwGOD app, together with the standard texts of the Mass.
Another important council was the one held at Trent during a number of separate meetings between 1545 and 1563. At Trent, answers were given to questions which had arisen during the Reformation. The most recent council is the Second Vatican Council, which took place between 1962 and 1965. Topics included the role of the lay faithful in the Church, and dialogue with other religions.
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This is what the Popes say
[The Council of] Chalcedon represents the sure goal of the Christology of the three previous Ecumenical Councils: Nicea in 325, Constantinople in 381 and Ephesus in 431. By the sixth century these four Councils that sum up the faith of the ancient Church were already being compared to the four Gospels... because on them, [Pope Gregory the Great] explains... "as on a four-square stone, rises the structure of the holy faith" [Pope Benedict XVI, General Audience, 5 Mar. 2008]