Before it was deemed "Christmas" and the birthday of Jesus Christ, the period of the winter solstice - ending on December 25th - was celebrated in various countries as the birth of the sun, who was considered a god in these many places.

The Christian celebration of "Christmas" was only formalized in the middle of the fifth century (450 AD/CE), when Emperor Julius I "assimilated the festival with that of the birth of Mithra (December 25), in order to facilitate the more complete Christianisation of the empire." Until that time, December 25th had been the birthday of Sol Invictus or the "Unconquered Sun," established as such by Emperor Aurelian in 274 AD/CE.

Concerning the origins of the solar holiday of December 25th vis-à-vis Christianity, the Catholic Encyclopedia ("Christmas") states:

"The earliest rapprochement of the births of Christ and the sun is in [the writings of early Church father] Cyprian [200-258]...'O, how wonderfully acted Providence that on that day on which that Sun was born…Christ should be born.'

"In the fourth century, [Church father] Chrysostom...says: ..."But Our Lord, too, is born in the month of December...the eighth before the calends of January [25 December]..., But they call it the 'Birthday of the Unconquered'. Who indeed is so unconquered as Our Lord...? Or, if they say that it is the birthday of the Sun, He is the Sun of Justice."

As we can see from these remarks, the birth of Christ at the winter solstice has been asserted since as early as the third century. Moreover, the reason for this birthdate is clearly given: This date represents "the birthday of the Sun!"

Before that time, the winter solstice was also celebrated in many other places, including in Egypt, where the baby sun god Horus was brought out in a manger for display. Concerning winter-solstice "Feasts and Festivals," the Encyclopedia Britannica reports, "The common people in China have a similar custom on the arrival of the winter solstice..." The Encyclopedia Britannica also names several other cultures as having winter celebrations, including the Mexicans and Peruvians. Even the Jews had their winter holiday, or "Feast of the Dedication," as mentioned in the New Testament at John 10:22. The winter solstice in Latin is called "bruma," serving as one source of the Roman celebration called "the Brumalia." There was also the December festival of Saturnalia in the Roman Empire, which ended at the winter solstice.

December 25th actually represents the end of the three-day period or triduum of the winter solstice, which begins at midnight on December 21st or the morning of December 22nd and ends at midnight on December 24th - "Christmas Eve" - or the morning of December 25th. This time represents the shortest days of the year, when the sun appears to be "dying." Thus, when the days start to lengthen again, the sun seems to have been "born," "reborn" or "resurrected." Hence, December 25th is the birthday of the sun!