I have no doubt that St George exists. But does it matter? I am reminded of this story from Elder Paisios (+1994):
I remember there was an amicable elderly monk in the Esphigmenou Monastery who was so sincere that he thought the Ascension of Christ was a saint. He would count his rosary and say: «Saint of God, take pray for us»! Once, a brother in the Elderly monk's home was ill and he didn't have anything to give him to eat. In two steps he goes downstairs, opens the window which looked at the sea, hangs out his hands to the sea and says: «Saint Ascension, give me a fish for my brother». And straight away – Oh! A miracle! Such a large fish jumps from the sea into his hands. The others, who saw him, were astonished. He was looking at them with a calm smile in his face. It was like saying: «What's so strange that you see? » We, the others said, have knowledge, we know when a Saint is celebrating, how another Saint was tormented, when the Ascension happened and where it happened and how, and still we can't have such a little fish! These are the strange things of spiritual life, which the logic of the intellectuals, who have within their mind themselves and not God, can't conceive because they have inside them the barren social knowledge along with the secular spiritual illness and the Holy Spirit is missing.
http://www.esphigmenou.gr/index_en.php?mid=5&sid=4&newsid=21