sourced story
380 CEReputable sourceWell documented

Christianity Becomes the State Religion

On the timeline · around 380 CE · Christianity Becomes the State Religion300 CE325 CE350 CE375 CE400 CE425 CE450 CE

What happened

In 380 CE the emperor Theodosius I issued the Edict of Thessalonica, making Nicene Christianity the official religion of the Roman Empire. Further laws soon restricted and then banned public pagan worship.

Why it matters

Within a lifetime of the Edict of Milan, Christianity went from merely tolerated to mandatory, ending Rome's long tradition of religious pluralism.

Sources