Who was the god born of a virgin in a cave on December 25th? Who died and was resurrected in order to become an intermediary god between man and the good god of light? Thats right - Mithras. Sound familiar.
Here is some more information from Dies Natalis Solis Invicti and Mithras
"Since earliest history, the Sun has been celebrated with rituals by many cultures when it began it's journey into dominance after it's apparent weakness during winter. The origin of these rites, Mithrasists believe, is this proclamation at the dawn of human history by Mithras commanding His followers to observe such rites on that day to celebrate the birth of Mithras, the Invincible Sun."
But the actual choice of December 25 for Christmas was thought to have been made under the Emperor Aurelian* because this was the date of the Winter Solstice and was the day devotees of Mithras celebrated the dies natalis solis invicti 'birthday of the invincible sun". ...(Cont)...
And here is a bit more info on MITHRAISM