Christians were persecuted throughout the Roman Empire, beginning in the 1st century AD and ending in the 4th century. Originally a polytheistic empire in the traditions of Roman paganism and the Hellenistic religion, as Christianity spread through the empire, it came into ideological conflict with the imperial cult of ancient Rome. Pagan practices such as making sacrifices to the deified emperors or other gods were abhorrent to Christians as their beliefs prohibited idolatry. The state and other members of civic society punished Christians for treason, various rumored crimes, illegal assembly, and for introducing an alien cult that led to Roman apostasy.[1] The first, localized Neronian persecution occurred under Emperor Nero (r. 54–68) in Rome. A number of mostly localized persecutions occurred during the reign of Marcus Aurelius (r. 161–180).[2] After a lull, persecution resumed under Emperors Decius (r. 249–251) and Trebonianus Gallus (r. 251–253). The Decian persecution was particularly extensive. The persecution of Emperor Valerian (r. 253–260) ceased with his notable capture by the Sasanian Empire's Shapur I (r. 240–270) at the Battle of Edessa during the Roman–Persian Wars. His successor, Gallienus (r. 253–268), halted the persecutions.
The Augustus Diocletian (r. 283–305) began the Diocletianic persecution, the final general persecution of Christians, which continued to be enforced in parts of the empire until the Augustus Galerius (r. 305–311) issued the Edict of Serdica and the Augustus Maximinus Daza (r. 310–313) died. After Constantine the Great (r. 306–337) defeated his rival Maxentius (r. 306–312) at the Battle of the Milvian Bridge in October 312, he and his co-emperor, Licinius, issued the Edict of Milan (313), which permitted all religions, including Christianity, to be tolerated.