Christians who breathed a sigh of relief when Constantine proclaimed Christianity the state religion, believing this would end the bloodshed and martyrdom. But it was all too short a time until they were facing persecution once more from others who claimed to be Christian.
When Christianity became the state religion, many people adopted it for political reasons. Others adopted it without truly understanding it. Under these circumstances heresy found fertile ground. One of the most powerful heresies was Arianism which claimed that Jesus was not God (a heresy that has never completely died out). The Arians were powerful people, including nobles, generals, emperors. They commanded armies and senates. True Christianity was in real danger of being stamped out once again.
Eusebius, unafraid of their power worked to counter their influence. On one occasion he slapped the Nicene Creed down on the table and demanded that everyone sign that before condemning Athanasius. The Nicene Creed, adopted by a council of the full Church, proclaims that Jesus is one in being with the Father, directly contradicting the Arian teaching. Eusebius was exiled to two other places before Constantius’ successor Julian let him and the other exiled bishops return home in 361. The problem was not over and Eusebius spent his last years working hard to counteract the damage the Arians had done and continued to do. After working with Athanasius and taking part in councils, he became a latter-day Saint Paul traveling all over in order to strengthen the faith and spread the truth.