Final answer:
The Great Schism of 1054 is the primary cause of division between the Catholic and Orthodox faiths. Linguistic, cultural, and theological differences also contribute to the divide.
Step-by-step explanation:
From the Catholic perspective, what divides the two faiths is primarily the Great Schism of 1054. This schism led to the division of the Christians into two factions: the Eastern Catholics, also known as Orthodox Christians, and the Western branch, which remained under the authority of the Pope in Rome. Linguistic, cultural, and theological differences further deepened the divide between the two factions. For example, the Eastern Orthodox Church used Greek, permitted married priests, and recognized other patriarchs as authoritative, while the Roman Catholic Church operated in Latin, insisted on a celibate clergy, and elevated the Pope as the final authority.