Answer to Question 1
A schism between the Roman Catholic and Eastern Orthodox churches occurred over the issue of iconography. Although religious imagery was essential to the growing influence of Christianity, the two branches of Christianity disagreed over the role of icons in divine worship. Most Christians held that visual representations of God the Father, Jesus, the Virgin, and the saints worked to inspire religious reverence. Others, however, adhering to the prohibition of graven images in the Hebrew Bible, considered images to be no better than pagan idols. During the eighth century, the issue came to a head when the Byzantine emperor Leo III inaugurated a policy of iconoclasm (image-breaking) that called for the wholesale destruction of religious sculpture and the whitewashing of mosaics and wall-paintings. The Iconoclastic Controversy, which remained unresolved until the middle of the ninth century, generated the schism between the Eastern and Western churches. Compounded by other liturgical and theological differences, that schism would become permanent in 1054.
Answer to Question 2
Byzantine church architects favored the Greek cross plan, by which all four arms of the structure were of equal length. At the crossing point rose a large and imposing dome. Inside the churches of Byzantium, the mosaic technique reached its artistic peak. A comparison of Byzantine mosaics with, for instance, any Roman paintings or sculptural reliefs underlines the vast differences between the aesthetic aims and purposes of Classical and Christian art. Whereas the Romans engaged a realistic narrative style to honor temporal authority, the Christians cultivated an abstract language of line and color to celebrate otherworldly glory.
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