The 626 Avar Siege and the Roman-Sasanian War marked a significant turning point in the political and religious identity of Constantinople. The city survived due to the strength of the Theodosian Walls and the naval weaknesses of the besiegers. Although the Avars and Persians failed, the siege reinforced the belief that Constantinople was a divinely protected city. In the absence of Emperor Heraclius, Patriarch Sergius took a leading role, and the people saw the victory as a divine intervention by Theotokos. However, veneration of Mary and the sanctity of icons were pre-existing beliefs rather than direct outcomes of the siege. The event contributed to the perception of Constantinople as the New Jerusalem, strengthening its image as a city under divine protection.
Faik Can Lüleci (Fri,) studied this question.