380 (State Religion)
In 379 Theodosius I became emperor and co-reigned with Gratian.
In February 380, the Edict of Thessalonica declared Nicene Christianity the state religion, criminalising Arianism and other heresies.
In 379 Theodosius I became emperor and co-reigned with Gratian.
In February 380, the Edict of Thessalonica declared Nicene Christianity the state religion, criminalising Arianism and other heresies.