Defining Moments in Early and Medieval Christian History

Posted on Oct 19, 2025 in Religion

Foundations of the Early Church (310–451 AD)

Constantine: Edict of Milan (310 AD)

Issued by Constantine, this edict ended the persecution of all religions, particularly Christianity.

The Council of Nicaea (325)

This Church Council addressed the Arian crisis and the Divinity of Christ. It produced the Nicene Creed and established the Doctrine of the Trinity: One God, Three Persons (One Divine Ousia; Three Hypostases or Personae).

Key Figures in the Arian Controversy
  • Arius: A priest who asserted, “There was a time when the Son was not,” arguing that the Son was a creature.
  • Athanasius: A bishop who defended the Trinity and the Divinity of the Son, maintaining that the Son was eternally Begotten and not made (not created).

The Council of Chalcedon (451)

This council addressed the Humanity of Christ, affirming that Christ is both Fully Divine and Fully Human. It solidified the Doctrine of the Incarnation and affirmed Mary as Theotokos (Mother of God/God-bearer).

Core Doctrines
  • Trinity: One God, Three Persons.
  • Incarnation: Jesus, the Christ, the Son, is fully human, fully divine; perfectly human, perfectly divine; the Word made Flesh.

Augustine (354–430)

A great theologian and writer of the late antiquity Western Church.

Augustine’s Key Concepts
  • Manichaeism: A Gnostic religion positing Good vs. Evil, or Light vs. Dark, as equal and opposite forces.
  • Definition of Evil: Evil is the lack, absence, or privation of Good; it is not a thing in itself. Evil is a parasite on the good and lacks true substance.
  • The City of God (De Civitate Dei): A work dealing with History and Salvation History. It explores ideas about the Sacred and Secular, Church and State, and Spiritual and Temporal working together, asserting that God works in history through both good and bad events to bring it to fullness, perfection, and completion.

Monasticism

Anthony (of Egypt) and Benedict (of Nursia) are recognized as the founders of monasticism in the East and West, respectively. Benedict wrote the famous Benedictine Rule, a book detailing how to live monastic life individually and corporately.

The Great Schism and Rise of Western Power

Eastern Orthodox vs. Western Roman Christianity

The official split, known as The Great Schism, occurred in 1054, though its causes developed over centuries. The main causes included:

  1. Celibacy requirements for clergy.
  2. Disputes over the date of Easter.
  3. Differences in language and culture.
  4. The addition of the Filioque clause in the Creed by the West (stating the Holy Spirit proceeds from the Father and from the Son).

Key Historical Terms

  • Romanitas: The essence, culture, or ideas associated with all things Roman or civilized.
  • Charles Martel: Mayor of the Palace who defeated the Moors in 732 at the Battle of Tours.

The Papacy and Church Reforms

Defining the Papacy

The Papacy is defined by three roles:

  1. Bishop of Rome.
  2. Successor of Peter.
  3. Head of the Universal Church.

Major Reforms and Conflicts

  • The Gregorian Reform: Initiated by the founding of Cluny in 909. Cluny was an independent monastery (free from the King or local Bishop) and tied directly to Rome, establishing a model of independence.
  • Investiture Controversy (1075): A conflict (e.g., with Henry IV) where the Pope secured the right to appoint Bishops and Abbots. This gained the Church significant freedom from secular state control.
  • College of Cardinals: Their main function is to elect the next Pope. This mechanism theoretically removes the election process from the hands of kings and princes, allowing Cardinals to be crucial in setting the direction of the Church.

The Crusades and the Inquisition

The Crusades

  1. Crusade in Spain (The Reconquista): Refers to the centuries-long endeavor of retaking Spain from Islamic/Moorish rule, which dated back to the early 700s AD. It was completed in 1492 by Ferdinand and Isabella.
  2. First Crusade: Pope Urban II called for the First Crusade at the Council of Clermont in 1095. The most successful crusade was the First, resulting in the capture of Jerusalem and the establishment of Latin Kingdoms in the area.
  3. End of the Crusades: There were eight official Crusades. The Fourth Crusade (1202) infamously sacked Constantinople and proceeded no further (during this era, the Hagia Sophia Basilica was under Roman Catholic control). The official end of the Crusades came when Acre (the port of Jerusalem) fell to Muslims in 1291.

The Inquisition

The Inquisition was an effort to eliminate Heresy (non-orthodox beliefs or practices).

Aspects of the Inquisition

  • Positive Contributions: The Inquisition established principles of questioning, witnesses, and degrees of guilt or innocence. Many of these principles have been carried into modern systems of justice and Church rules.
  • Spanish Inquisition: (Contrasted with the general Medieval Inquisition) This was slightly more severe than the Medieval Inquisition, often resulting in Muslims and Jews being forced to convert.