As you can see it is written in what appears to be Greek. However, some of the letters of the words are replaced by Latin characters namely C, W, and backwards Gamma. These are not Modern or ancient Greek letters.
My guess is that due to the origins of Greek orthodoxy, The byzantine empire a.k.a eastern roman empire, caused the church to use latin letters due to the western roman influence. Am I right? If this is true, how come they only remained prominent in orthodox churches and have not replaced letters of the Modern greek alphabet?
C is a sigma, what you see as W is an omega. I'm not sure what letter you think is a backwards gamma, perhaps you could identify it in the picture. All Greek letters here.
