The answer
The Church identifies its saints and angels with a halo of light around their heads in their icons, referring to their nature as being the “light of the world.” Icons of Christ are often further distinguished by a cross inside the halo together with the first and last letters of the Greek alphabet, alpha and omega (Rev. 1:8), included as a sign of the Lord’s Divinity. The following are some points which characterize Coptic halos:
a. Halos are never used around the head of any living person, contrary to Western
Church customs.
b. No other shapes than the circular halo are known in Coptic icons; i.e., no triangular,
quatrefoil, or plates above the head are used.
c. There are icons found in the Monastery of Bawit in Southern Egypt, dating back to
the sixth century, that show a halo surrounding the entire body of Christ on the throne or during His ascension as a sign of His Divinity.
d. In the Coptic Church, the halo does not only refer to power, but it is also a sign of
divinity, holiness, and beauty. Consequently, you never see it displayed around the head of Satan, as in some Greek, Saxon, and French pictures.
Fr. Tadros Yacoub Malaty