Since the 4th century and particularly since the Edict of Thessalonica in 380, the defense and promotion of Christianity has been a key driver of Imperial identity. After that date, however, the territorial scope of the Empire or any of its continuating entities has never exactly coincided with that of Christendom, and the discrepancies led to enduring conflicts of legitimacy. The most consequential of these was the East-West Schism, which crystallized in 1054 as a consequence of longstanding fights over governance and jurisdiction (known as ecclesiastical differences) and over doctrine (theological differences), and can be fairly viewed as a delayed effect of the problem of two emperors arising from the creation of the Carolingian Empire in 800.