The word is not special to Christianity. One of the names of Zeus was Epiphanes (the manifest one), and festivals in his honour were called "Epiphanies." (Greek, epi-phaino, to shine upon, to be manifest [in creation].)
Episemon in Greek numerals, is a sign standing for a numeral. Thus, epishmou bau generally called
Fau, Episemon, stands for 6, and iota-episemon for 16. There are two other symbols - viz. koppa
for 90, and sampi [san-pi] for 900. The reason is this: The Greek letters were used for numerals, and
were ranged in three columns of nine figures each; but 24 letters will not divide by 9, so the 3 symbols,
episemon, koppa, and sampi were added to make up 3 × 9. Col. 1, from 1 to 20; col. 2, from 20 to 100; col.
3, from 100 to 1,000.
Bau and Fau are identical, the B or F being the dijamma. Thus oiuoz (wine) was
pronounced Foinos, called in Latin Vinum, and wou (an egg) was pronounced Ofon, in Latin Ovum.
A
dash under a letter multiplied it a hundredfold. Thus, a = 1, but = 000. For intermediate figures between
full tens a mark was made above the unit. Thus i (iota = 10; but ia = 10 + 1 = 11, ib = 10 + 2 = 12; ig
= 10 + 3 = 13, and so on.