Answer:
The recognition of Christianity as the official religion of the Roman Empire was made by Emperor Constantine in the Edict of Milan in the year 330 of our era.
When Christianity ceased to be persecuted and officially replaced the beliefs of paganism among the Romans, Latin art has been determined by some historians. But it must be more appropriately called Primitive Christian Art itself.
This phase, early Christian art, developed from the 330's to the 500's, when the arts of Christianity began to split into two major branches - one eastern and one western.