c. 49
Council of Jerusalem
The apostles and elders at Jerusalem decide that Gentile converts need not be circumcised or keep the whole law; the decision that makes a Gentile church possible.
The Councils
The assemblies that defined the faiths, gathered across every tradition's timeline.
c. 90 CE
Council of Yavneh
The sages gathered at Yavneh under Rabban Gamaliel II consolidate the canon and the order of prayer after the Temple's fall; later tradition remembered the gathering as a council, and modern scholarship reads it as a gradual consolidation.
325
First Council of Nicaea
Constantine convenes the first ecumenical council at Nicaea, which condemns Arius and confesses the Son as homoousios; of the same being as the Father; in the original Nicene Creed.
381
First Council of Constantinople
The second ecumenical council completes the Nicene confession, expanding the article on the Holy Spirit; its creed is the Nicene-Constantinopolitan Creed the church still recites.
431
Council of Ephesus
The third ecumenical council condemns Nestorius and confesses Mary as Theotokos, God-bearer; the Church of the East separates in the aftermath; the first lasting schism.
451
Council of Chalcedon
The fourth ecumenical council confesses Christ in two natures, without confusion or separation; the churches that refuse the definition become the Oriental Orthodox communion.
553
Second Council of Constantinople
The fifth ecumenical council condemns the Three Chapters in Justinian's bid to reconcile the Chalcedonian and non-Chalcedonian churches; the reconciliation fails.
680–681
Third Council of Constantinople
The sixth ecumenical council condemns Monothelitism and confesses two wills in Christ, vindicating Maximus the Confessor a generation after his death.
787
Second Council of Nicaea
The seventh ecumenical council restores the icons and defines the distinction the church still uses: veneration (proskynesis) for images, true worship (latreia) for God alone.
1095
Council of Clermont; First Crusade Called
Urban II preaches at Clermont and calls the armed pilgrimage to the Holy Land; the crusading movement begins.
1215
Fourth Lateran Council
Innocent III's council defines transubstantiation, requires annual confession and Easter communion, and legislates for the medieval church at its most confident.
1545–1563
Council of Trent
Across eighteen years and three convocations, Trent defines Catholic doctrine against the Reformation and reforms the clergy; the Tridentine settlement governs Catholic life for four centuries.
1869–1870
First Vatican Council
Vatican I defines papal infallibility in Pastor Aeternus; the Old Catholic churches separate in refusal, and the council suspends unfinished as Rome falls to Italy.
1962–1965
Second Vatican Council
John XXIII's council renews the Catholic Church for the modern world: the liturgy in the vernacular, religious liberty confessed, ecumenism embraced, and the church's posture toward Judaism reversed in Nostra Aetate.