The 280-year comment of existence being ‘illegal’ is false. The Romans allowed virtually every single region they conquered to continue their internal religious situation. The Jews, the Egyptians, etc....all continued their practices allowed by public standards, to continue under the Roman Empire.
>>>The 280-year comment of existence being ‘illegal’ is false
Most works of Christian history say Christianity became legal with the Edict of Milan, which was passed in 313 AD.