No unfortunately not. The wonderful christian bumper sticker is unfortunately incorrect. It should read Emperor Constantine is the reason for the season… Christianity has nothing to do with it. Thank Mithra
Mithra was an embodiment of the sun, so this period of its rebirth was a major day in Mithraism, which had become Rome’s latest official religion with the patronage of Aurelian. It is believed that the emperor Constantine adhered to Mithraism up to the time of his conversion to Christianity. He was probably instrumental in seeing that the major feast of his old religion was carried over to his new faith” (The Christmas Almanac, 1979, p. 17).