When a question about the faith divided Christians, the bishops met in council and gave a ruling. This timeline starts with the meeting of the apostles and elders in Jerusalem and then quotes thirteen of the Church's general councils, from Nicaea in 325 to the Second Vatican Council. Each entry gives the council's own words on the main question before it.
Drafted from primary sources. Every quotation is checked against the page it links to. The Catholic Church counts twenty-one ecumenical councils; thirteen are quoted here. The translations are those of the linked pages.
“For it has seemed good to the Holy Spirit and to us to lay upon you no greater burden than these necessary things: that you abstain from what has been sacrificed to idols and from blood and from what is strangled and from unchastity.”
“We believe in one God, the Father Almighty, maker of all things visible and invisible; and in one Lord Jesus Christ, the Son of God, the only-begotten of his Father, of the substance of the Father, God of God, Light of Light, very God of very God, begotten (γεννηθέντα), not made, being of one substance (ὁμοούσιον, consubstantialem) with the Father.”
“And in the Spirit, the holy, the lordly and life-giving one, proceeding forth from the Father, co-worshipped and co-glorified with Father and Son, the one who spoke through the prophets; in one, holy, catholic and apostolic church.”
“This is the account of the true faith everywhere professed. So shall we find that the holy fathers believed. So have they dared to call the holy virgin, mother of God, not as though the nature of the Word or his godhead received the origin of their being from the holy virgin, but because there was born from her his holy body rationally ensouled, with which the Word was hypostatically united and is said to have been begotten in the flesh.”
“So, following the saintly fathers, we all with one voice teach the confession of one and the same Son, our Lord Jesus Christ: the same perfect in divinity and perfect in humanity, the same truly God and truly man, of a rational soul and a body; consubstantial with the Father as regards his divinity, and the same consubstantial with us as regards his humanity; like us in all respects except for sin; … one and the same Christ, Son, Lord, only-begotten, acknowledged in two natures which undergo no confusion, no change, no division, no separation; at no point was the difference between the natures taken away through the union, but rather the property of both natures is preserved and comes together into a single person and a single subsistent being”
“If anyone does not confess his belief that our lord Jesus Christ, who was crucified in his human flesh, is truly God and the Lord of glory and one of the members of the holy Trinity: let him be anathema.”
“And we proclaim equally two natural volitions or wills in him and two natural principles of action which undergo no division, no change, no partition, no confusion, in accordance with the teaching of the holy fathers. And the two natural wills not in opposition, as the impious heretics said, far from it, but his human will following, and not resisting or struggling, rather in fact subject to his divine and all powerful will.”
“…we decree with full precision and care that, like the figure of the honoured and life-giving cross, the revered and holy images, whether painted or made of mosaic or of other suitable material, are to be exposed in the holy churches of God … Certainly this is not the full adoration {latria} in accordance with our faith, which is properly paid only to the divine nature … Indeed, the honour paid to an image traverses it, reaching the model, and he who venerates the image, venerates the person represented in that image.”
“His body and blood are truly contained in the sacrament of the altar under the forms of bread and wine, the bread and wine having been changed in substance, by God’s power, into his body and blood, so that in order to achieve this mystery of unity we receive from God what he received from us.”
“We profess faithfully and devotedly that the holy Spirit proceeds eternally from the Father and the Son, not as from two principles, but as from one principle; not by two spirations, but by one single spiration.”
“We also define that the holy apostolic see and the Roman pontiff holds the primacy over the whole world and the Roman pontiff is the successor of blessed Peter prince of the apostles, and that he is the true vicar of Christ, the head of the whole church and the father and teacher of all Christians, and to him was committed in blessed Peter the full power of tending, ruling and governing the whole church, as is contained also in the acts of ecumenical councils and in the sacred canons.”
“This disposition, or preparation, is followed by Justification itself, which is not remission of sins merely, but also the sanctification and renewal of the inward man, through the voluntary reception of the grace, and of the gifts, whereby man of unjust becomes just, and of an enemy a friend, that so he may be an heir according to hope of life everlasting.”
“…we teach and define as a divinely revealed dogma that when the Roman pontiff speaks EX CATHEDRA, that is, when, in the exercise of his office as shepherd and teacher of all Christians, in virtue of his supreme apostolic authority, he defines a doctrine concerning faith or morals to be held by the whole church, he possesses, by the divine assistance promised to him in blessed Peter, that infallibility which the divine Redeemer willed his church to enjoy in defining doctrine concerning faith or morals.”
“Since the Church is in Christ like a sacrament or as a sign and instrument both of a very closely knit union with God and of the unity of the whole human race, it desires now to unfold more fully to the faithful of the Church and to the whole world its own inner nature and universal mission. This it intends to do following faithfully the teaching of previous councils.”