1
325 AD
First Council of Nicaea
- Emperor Constantine
- Arianism and the full divinity of the Son
- Traditionally remembered as 318 bishops
Ecumenical Councils
2
381 AD
First Council of Constantinople
- Emperor Theodosius I
- The Holy Spirit, Nicene faith, and lingering Arian controversy
- About 150 bishops
3
431 AD
Council of Ephesus
- Emperor Theodosius II
- Nestorian controversy and the unity of Christ's person
- About 200 bishops
4
451 AD
Council of Chalcedon
- Emperor Marcian
- How to confess Christ as fully God and fully man
- About 520 bishops
5
553 AD
Second Council of Constantinople
- Emperor Justinian I
- Chalcedonian reception, anti-Nestorian clarification, and the Three Chapters
- About 165 bishops
6
680-681 AD
Third Council of Constantinople
- Emperor Constantine IV
- Monothelitism and Christ's human will
- About 170 bishops
7
787 AD
Second Council of Nicaea
- Empress Irene and Emperor Constantine VI
- Iconoclasm and the veneration of holy images
- About 350 bishops