The decline of the Roman Empire began after Marcus Aurelius' death. The leaders took control of the empire but they were weak leaders. Many candidates who wanted to get the position. The military in the empire was strong but they did not cooperate with the ruler. Therefore, the Romans hired Barbarians for the Roman military service. Since Barbarians were hired for military purpose, they took advantage of invading the Roman Empire. Some of the Germanic tribes tried to start a war with the Roman Empires and to destabilize the government. With all these disadvantages, the Roman Empire slowly declined until the Roman Empire taken over by Diocletian. After ruling the entire Roman Empire for a couple of years, Diocletian came to a solution that it was too hard to control the Roman Empire by himself. Therefore, he decided to split it into the East and West Empires and appointed his coworker to the West Empire. The division did not help, because eventually the East and West Empires fought against each other for the ruling rights.
             The rise of Christianity began a couple of years after crucifying Jesus Christ. After Jesus rose from the dead, he sent helpers to his people. The Holy Spirit was sent by God to help us and to show what is right and wrong. During that time, the Romans setup the roadways between the major cities for trade goods. Therefore, it was easier to spread the gospel between nearby countries and the ship trades helped to move Christianity to the other side of the world. The major sea was the Mediterranean Sea, which connected Lower Egypt with Rome.
             The health problems intervened with the fall of the Roman Empire. Water was brought though lead pipes where rats and mice lived and reproduced. In some incidents, rats would die in the pipes, therefore water that went through the city was contaminated with all kinds of diseases. These things brought health problems to the Roman cities. The trash was piled up on the streets...