306 CE- Constantine becomes Emperor. Before Constantine, the Roman Empire was a primarily polytheistic civilization, which meant that people recognized and worshiped multiple gods and goddesses. Historically, Jews and later Christians had been persecuted in ancient Rome. Constantine increased religious tolerance for Christians and eventually would convert to Christianity (on his deathbed). In 380 CE, the emperor Theodosius issued the Edict of Thessalonica, which made Christianity the official religion of the Roman Empire. Eventually, the position of the leader of the Roman Catholic Church, the Pope, who still presides in Rome (Vatican City), would become the most influential and powerful person in all of Europe, even greater than that of Kings. Historians argue that Constantine's conversion to Christianity is one of the most important events in the growth and spread of the religion.