The symbol of a fish is sometimes used by Christians (you might see a fish sticker on a car or someone wearing a little fish badge). This comes from the time when the first Christians had to meet in secret, as the Romans wanted to kill them (before Emperor Constantine became a Christian). Jesus had said that he wanted to make his followers ‘Fishers of Men’, so people began to use that description.
When two Christians met, one person drew half a basic fish shape (often using their foot in the dust on the ground) and the other person drew the other half of the fish. The Greek word for fish is ‘Ikthus’ or ‘Ichthys’. There are five Greek letters in the word. It can also comprise of a sentence of Christian beliefs ‘Ie-sous Christos Theou Huios So-te-r’ which in English means “Jesus Christ, Son of God, Saviour”. The second letter of these five letters is X or Christos!
So Xmas can also mean Christmas, rather it should also be called ‘Christmas’ rather than ‘ex-mas’!