Arrival of Christianity and rise of Byzantine Empire

Christianity arrived in Greece with the preachings of St. Paul during the 1st century AD, and eventually spread throughout Greece and the Roman Empire. In the 4th century, Roman Emperor Constantine the Great legalized Christian worship and declared it the state religion of the empire. He moved the capital of the empire from Rome to Byzantium (present-day Istanbul), which he renamed Constantinople. Internal divisions eventually divided the Roman Empire into a western half (the West Roman Empire) and an eastern half (East Roman Empire.) The West was eventually invaded and sacked by invaders from northern Europe, while the East survived for another millennium as the Byzantine Empire with Constantinople as its capital.