Answer: Civil War
Explanation:
The emperor Diocletian had divided the Roman empire into sub-empires that were ruled by co-emperors. Very soon however, these emperors began to fight each other for control of the entire empire. In the end, two were left: Constantine the Great and Licinius in the Eastern empire.
Constantine then claimed to be fighting under the Christian God and united his soldiers under the Cross. This led him to victory against Licinius and afterwards he allowed Christianity to become legal in the empire as the state religion which led to it spreading across the empire.
It was the ideal time to turn to Christianity because people tend to turn to a higher power during times of conflict so as to gain inspiration and strength.
