The ancient Greek theater, before it developed into a Hellenistic entertainment event and then into a Roman arena with beast battles, duels and bloody killings of innocent people to the delight of the enraged citizens of the Roman decadence, had a ritualistic and educational character.
Aeschylus gave to theater its character with the scenery, dialogues and extras and later, after Aristophanes it was desanctified. However, it still had a didactic character.
The early Christian churches on the contrary, the Churches with synthrona clearly had influences from the ancient theater and the Ecclesia of Demos. But it is also possible that its ritual, by Greek scholars and Greek-studied Christian philosophers, may have direct influences from ancient rituals.
These are some photos of preserved synthrona of early Christian churches:
Agios Nikolaos, Demre, modern Turkey.
Agia Irini, Constantinople, modern Turkey
Hagia Sophia, Nice, modern Turkey
Amoria, modern Turkey