How Charlemagne Changed Christianity

One Emperor Reshaped Christianity and Strengthened the Church’s Grip on Power

After the fall of the Western Roman Empire, the Latin-speaking world became theologically disconnected from the Greek East. By the time Charlemagne came to power in the late 8th and early 9th centuries, he sought to establish the Franks as the new Christian empire, independent from Byzantine authority. This led to fundamental changes in Christian doctrine and practice, shaping what would later become Western Christianity.

The Filioque Insertion: The Theological Break

One of Charlemagne’s most significant actions was pushing the Filioque clause into the Nicene Creed. The original Creed, established at the Councils of Nicaea (325) and Constantinople (381), affirmed that the Holy Spirit proceeds from the Father (John 15:26). However, Charlemagne’s theologians added the phrase “and the Son” (Filioque) to assert a different understanding of the Trinity — one that undermined the monarchy of the Father and broke with early Church teaching.

Charlemagne used this theological alteration as a political tool to delegitimize Byzantine Orthodoxy and elevate his Frankish Empire’s version of Christianity. Initially, even the Popes in Rome rejected the Filioque, but Charlemagne aggressively promoted it in his territories. Eventually, the Latin Church embraced the modification fully, leading to one of the key theological divides that contributed to the Great Schism of 1054.

Charlemagne’s Suppression of Byzantine Christianity

1. Declared the Byzantine Church heretical — He commissioned the Libri Carolini, which attacked Byzantine theology, particularly their use of icons, even though the Byzantine Church had already resolved the issue at the Seventh Ecumenical Council.

2. Created a “Frankish Christianity” — He promoted Augustine’s ideas over those of the Cappadocian Fathers, shifting the emphasis toward legalistic and philosophical interpretations rather than the mystical and participatory theology of the early Church.

3. Politicized the Papacy — He turned the Pope into a figure who served Frankish interests rather than the broader, conciliar unity of the Church. This transformed the Papacy into a Western imperial institution, rather than the “first among equals” model of the early Church.

The Western Narrative and the Erasure of the East

After Charlemagne, the West systematically rewrote history to frame itself as the true inheritor of Christianity, ignoring or downplaying the Byzantine Church. This included:

• Calling figures like Augustine a “Church Father” while sidelining the actual Fathers who shaped Christian doctrine.

• Presenting the Papacy as the sole authority over Christianity, instead of the conciliar model of the Seven Ecumenical Councils.

• Promoting penal substitution as the dominant atonement model, replacing the Orthodox view of Christ conquering death.

• Introducing heresies such as “original sin” and “blood atonement”, which were foreign to early Christian teaching and distorted the understanding of salvation.

• Framing Byzantium as corrupt or heretical, when in reality, the Byzantine Church preserved the original faith while the West innovated.

Legacy and Impact

The changes implemented by Charlemagne and his successors did not merely affect medieval politics; they reshaped Christianity itself. Western theology became increasingly legalistic, focused on sin and debt, whereas the Eastern Church retained the original Christian vision of salvation as participation in divine life. The political power Charlemagne gave to the Papacy eventually led to the rise of the medieval Catholic Church and later conflicts such as the Reformation.

The divergence between East and West was not just a theological disagreement but a fundamental shift in how Christianity was understood and practiced. The erasure of the Eastern Church in Western history books is one of the great historical revisions of Christendom. Charlemagne’s efforts to create a Frankish Christianity led to centuries of misunderstanding about the early Church and its teachings.

Recognizing these historical developments is crucial to understanding why Christianity looks so different in the East and the West today. The Byzantine Church preserved the faith unchanged, while the West gradually moved further away from the original theological foundations, influenced heavily by the political and ideological ambitions of the Carolingian ruler

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