Religion played a very important role in the daily life of Ancient Rome and the Romans. At first, Romans believed in many different gods and goddesses. These gods were like people, but with magical powers. The Roman gods were part of a family. Roman religion was centred around gods and explanations for events usually involved the gods in some way or another. The Romans believed that gods controlled their lives and, as a result, spent a great deal of their time worshipping them. Each god or goddess looked after different people or things, the most important god was Jupiter.
Christianity was banned and the early converts to Christianity in Ancient Rome faced many difficulties. The first converts were usually the poor and slaves as they had a great deal to gain from the Christians being successful. If they were caught, they faced death for failing to worship the emperor. In AD 313, the Emperor Constantine made Christianity legal and for the first time, they were allowed to openly worship. Churches were quickly built not just in Rome but throughout the empire. In AD 391, the worship of other gods was made illegal.
References
http://www.bbc.co.uk/schools/primaryhistory/romans/religion/
http://www.historylearningsite.co.uk/ancient-rome/ancient-rome-and-religion/
http://www.historylearningsite.co.uk/ancient-rome/rome-and-christianity/