Panel of painted ceiling, nave
The Alpha (A) and the Omega (Ω): the first and last letters of the Ancient Greek alphabet respectively.
I am Alpha and Omega, the beginning and the end, says the Lord God who is and who was and who is to come, the Almighty. Rev. 1:8
In the manner of the ancient Christians, we too adorn the vaulted ceiling with the Alpha and Omega. See below a late 4th century depiction of Christ between these symbols from the vault of the cubiculum leonis in the catacombs of Commodilla (Rome).