With Agustus being removed from the throne non-Italians began to gain power which took the original values of Rome away. The inconstancy of rulers caused tension because the people could not adjust to the new rulers.
The Christian believes didn't agree with the ones of Rome so it cause tension between the groups and persecution of Christians. A Christian became ruler and ended the persecution, but the spread of Christianity increased. This spread also caused tension because Christians believed that there was only one god which meant that the people lost respect for the rulers.
Slavery was a controversial topic and with the other countries not accepting it the Romans became behind in the worlds culture. People didn't accept their actions and the surrounding countries were angered which eventually added to the fall of the empire as a whole.