Greek Influence
In some ways Roman religion started out similar to the Greek religion but in other ways it was very different. Like the Greeks, the Romans believed there were many gods, and that these gods each controlled different parts of the world such as storms, the ocean, blacksmithing, etc.
At first the Roman gods were separate from Greek gods. Later on, as the Romans met more Greeks and began to admire the Greek's religion. The Romans adopted many Greek Gods as their own and began to worship them as well. As the Roman Empire expanded and grew, people also began to worship the gods of other conquered areas, like the Egyptian goddesses and Syrian gods.
At first the Roman gods were separate from Greek gods. Later on, as the Romans met more Greeks and began to admire the Greek's religion. The Romans adopted many Greek Gods as their own and began to worship them as well. As the Roman Empire expanded and grew, people also began to worship the gods of other conquered areas, like the Egyptian goddesses and Syrian gods.
Emperors
For the Romans, as well, their emperors were seen as gods or something close to that matter, depending on who you asked. Generally in the eastern part of the Roman Empire, like in Egypt and West Asia, people worshipped the emperors as gods. But in the western part, in Europe, people worshipped only the emperor's guardian angel, not the emperor himself.
Not everybody in the Roman Empire worshipped the emperors, or even the traditional Roman gods. When the Romans conquered the Jews about 100 BC, the Jews continued to worship their own god. Soon after that, when people began to become Christians, they also refused to worship traditional Roman gods. The Roman government didn't like it when the Jews and Christians refused to worship traditional Roman gods.
Not everybody in the Roman Empire worshipped the emperors, or even the traditional Roman gods. When the Romans conquered the Jews about 100 BC, the Jews continued to worship their own god. Soon after that, when people began to become Christians, they also refused to worship traditional Roman gods. The Roman government didn't like it when the Jews and Christians refused to worship traditional Roman gods.
Christians
Christianity slowly became more common until in 313 AD. The Roman Emperor Constantine became a Christian, and that influenced most rich people in the Roman Empire to become Christians. By 395 AD, the Roman Emperor Theodosius made it illegal not to be a Christian anywhere in the Roman Empire. Despite this law, however, only rich people and people in cities were really Christians at this time. After the fall of Rome is when the poor, such as the farmers, became Christians.