Final answer:
The Latin phrase filioque was added to the Nicene Creed by the Western church to clarify the Trinity, leading to a significant theological objection from the Eastern church and contributing to the Great Schism.
Step-by-step explanation:
The Latin phrase filioque, which means "and from the son," was added to the Nicene Creed by the Western church to clarify the Trinity. This addition emphasized that the Holy Spirit proceeds not only from the Father but also from the Son, which was a point of contention between the Western and Eastern churches. The Eastern church, which used Greek and held different views on ecclesiastical authority, objected to this unilateral addition by the Western church, as it did not recognize the authority of the Pope in the same way that the Western church did. This issue was one of the theological disagreements that contributed to the Great Schism of 1054, which split Christianity into Western (Roman Catholic) and Eastern (Orthodox) branches. The filioque controversy is indicative of the deep-rooted linguistic, cultural, and theological differences between the two branches of Christianity.