What role did Christianity play in the changes that occurred to the Roman Empire?

Christianity played a major role in the changes that occurred in the Roman Empire. With the reign of Emperor Constantine, Rome no longer had a monotheistic religion anymore. Romans used to believe that their emperor was a god, but with the insertion of Christianity, Romans no longer believed that and it hurt the credibility of the emperors authority. With the role of emperor having no credibility to the citizens, the fall of Rome was inevitable.