Theological Differences: The Byzantine Empire and the West had long developed distinct theological practices and doctrinal interpretations. The Great Schism of 1054, which formally split the Christian Church into Eastern Orthodox and Roman Catholic branches, was the culmination of centuries-old theological disagreements. The Byzantines viewed Western Christians as heretics due to differences in practices and beliefs, such as the authority of the Pope and the use of unleavened bread in the Eucharist.
Political and Territorial Rivalry: The Byzantine Empire and Western Christian states had competing political and territorial interests. The Crusades, launched by Western European rulers, were perceived by the Byzantines as attempts to expand Western influence and control over territories that had traditionally belonged to the Byzantine Empire. The Byzantines feared the power and ambition of Western Christian kingdoms, such as the Normans and the Venetians, who sought to expand their territories at the expense of the Byzantine Empire.
Cultural Differences: The Byzantine Empire and Western Europe developed different cultural identities over the centuries. The Byzantines viewed themselves as the true heirs of the Roman Empire and considered Western European cultures to be barbaric and uncivilized. They perceived the West's lack of respect for Byzantine culture and traditions as a threat to their identity and heritage.
Economic Competition: The Byzantine Empire and Western European merchants competed for control over trade routes and economic resources. The rise of Italian city-states, such as Venice and Genoa, challenged the Byzantine Empire's dominance in trade and commerce. The Byzantines feared the economic power and influence of Western Christian merchants, who often enjoyed favorable trading privileges and posed a threat to Byzantine economic stability.
These factors contributed to the Byzantine Empire's distrust of Western Christians, leading to tensions, conflicts, and mutual suspicion between the Eastern Orthodox and Roman Catholic worlds for centuries.