This latter solarist emperor decreed Sol's promotion to chief god in the late third century."The sun-god, Helios or Sol as distinct from Apollo, had not played an overly important role in Greek religion at the time of Pericles or Plato. It was the natural climax of a development extending over centuries when Aurelian proclaimed the 'Never Vanquished Sun' (...'Sol Invictus') the supreme divinity of the Roman Empire." (Erwin Panofsky, Meaning in the Visual Arts, Albrecht Durer and Classical Antiquity, p. Emperor Aurelian came by his solarist views honestly, he learned them on his momma's knee: she was a priestess of the sun.
He can be a surprisingly minor deity like the Greek Helios, Hyperion, or Sol in his original Roman garb; or he can be a major deity like Apollo, a sometime sun god.At a fairly late date, December 25th turns up: "Brethren, observe the festival days; and first of all the birthday which you are to celebrate on the twenty-fifth of the ninth month;. ." (Apostolic Constitutions, Book 5, Section 3, Chapter XIII, p. ('Ninth' month may seem off, but it occurs alongside a discussion of passover as occurring in the first month; counting from April, December is the ninth month). The Protestant authors who originated the accusation did not, of course, claim that Jesus did not exist nor that He was copied from these deities.They sought rather to point out that the Bible does not provide His birth-date, nor did the church of the first few Christian centuries know much about it.Thus liberated to do meteorology, he fried her with his thunder-bolt.He dissected her unborn child from her smoking body and, quite naturally, sewed it into his thigh, where the child grew to term.Some people, including Fox News anchormen, seem to know little about Christianity other than that Christianity is that religion which celebrates the Savior's birth on December 25th.
But wait a minute,— some Christians, like the Puritans of old, and the Seventh Day Adventists of the present day, do not celebrate Jesus' nativity at all, and others, like the Eastern Orthodox, do celebrate Christ's birth, but not on this day.
The quality of the argumentation establishing their new solar identity is displayed by Macrobius: "That Adonis too is the sun will be clear beyond all doubt if we examine the religious practices of the Assyrians...
In the story which they tell of Adonis killed by a boar the animal is intended to represent winter, for the boar is an unkempt and rude creature delighting in damp, muddy, and frost-covered places and feeding on the acorn, which is especially a winter fruit.
And so winter, as it were, inflicts a wound on the sun, for in winter we find the sun's light and heat ebbing, and it is an ebbing of light and heat that befalls all living creatures at death." (Macrobius, The Saturnalia, Book I, Chapter 21:1-4). The boar is damp and muddy, kind of like winter, so Adonis is really the sun.
What about those boars who are dry and fluffy, snorting in the summer sun? According to Macrobius, not only are the dying-and-rising vegetation gods really the sun, but so are Mars, Jupiter, Saturn, Hercules, and the whole rest of the pagan crew.
Perhaps mindful that Paul scolded the Galatians for observing days, "Ye observe days, and months, and times, and years" (Galatians ), the earliest authors show no interest in fixing this day.