Every year at Christmas time the web is filled with people jeering at Christians. Such is the society we live in. A common jeer is to shout exultantly that Christmas is really a pagan festival. In years gone past these people mocked that it was really the birthday of Mithras.
It looks as if my efforts with the Mithras wikipedia page are bearing fruit. Far fewer of these fools are appearing in fora, and people are offering refutations.
I need hardly say that no ancient text or inscription records any “birthday” for Mithras. The idea that it does is a confusion with the late Roman state sun god, Sol Invictus. There is a record of a festival on 25 Dec. for the latter, in 354 AD, in the calendar included in the Chronography of 354. This says simply “Natalis Invicti”.
This is pretty certainly a festival for Sol Invictus. The ancient festivals have fewer chariot races than the ones from late antiquity, and the Natalis Invicti has the substantial number of 24 listed.
The word “natalis” can mean “birthday”; but it can also mean the anniversary of the dedication of a temple. Since no source indicates that the sun came into being at one precise date — indeed the idea is ridiculous — it is probably the anniversary of the dedication of the splendid temple by Aurelian in 274 AD.
So how does Mithras come into this? Well Mithras is labelled Deus Sol Invictus Mithras almost from the earliest inscriptions, ca. 100 AD. But “deus sol invictus” seems to have been a cheap epithet. Quite a few deities use it, as meaning only “invincible sun god”. To identify all these would be as silly as supposing that everyone called John Smith was the same. Doubtless someone, of limited education and less scepticism towards anything he found convenient, stumbled across this and fell into this error. Knowing that few people had ever heard of Sol Invictus, he chose to mention Mithras.
But as I say, I am heartened. None of us benefit from the wrong raw facts getting into circulation, after all; and it feels as if my efforts have done some good.