Final answer:
The spread of Christianity significantly altered Roman society by transforming religious practices, fostering the growth of the Christian Church as a social and economic force, and linking secular power to Christian identity, which influenced political structures and alliances.
Step-by-step explanation:
The spread of Christianity and its acceptance by emperors profoundly altered Roman society from its earlier antiquity in several ways. Most significantly, it transformed religious practices and challenged the traditional Roman beliefs, which had been polytheistic. This religious transformation of society encouraged the growth of the Christian Church as a powerful social and economic institution, particularly in the cities of the eastern Mediterranean where bishops oversaw the construction of monasteries and churches.
Furthermore, the Imperial sponsorship of Christianity linked secular power to a Christian identity, enabling the rise of different regional alliances and rivalries as the Empire began to fracture. Christianity offered a strict monotheism that opposed the worship of Roman emperors and refused to participate in state cults, which sometimes led to persecution when perceived as a threat to societal hierarchy.
Finally, Constantine's conversion to Christianity and establishment of a new capital in Constantinople signaled a shift towards a Christian government which later worked to manage the church and Christian orthodoxy through various means including ecumenical councils and laws. These developments marked a decline in the traditional polytheistic worship and an eastward shift in the empire's power.