An extract from The Paganism that is Modern Day Christianity by Misha'al Al-Kadhi
Let us now move on to the "birthday of Jesus", Christmas. Jesus (pbuh) is commonly considered to have been born on the 25th of December. However, it is common knowledge among Christian scholars that he was not born on this day. It is well known th at the first Christian churches held their festival in May, April, or January. Scholars of the first two centuries AD. even differ in which year he was born. Some believing that he was born fully twenty years before the current accepted date. So how was the 25th of December selected as the birthday of Jesus (pbuh)?
Grolier's encyclopedia says: "Christmas is the feast of the birth of Jesus Christ, celebrated on December 25.... Despite the beliefs about Christ that the birth stories expressed, the church did not observe a festival for the celebration of the event until the 4th century.... since 274, under the emperor Aurelian, Rome had celebrated the feast of the "Invincible Sun" on December 25. In the Eastern Church, January 6, a day also associated with the winter solstice, was in itially preferred. In course of time, however, the West added the Eastern date as the Feast of the Epiphany, and the East added the Western date of Christmas".
So who else celebrated the 25th of December as the birth day of their gods before it was agreed upon as the birth day of Jesus (pbuh)? Well, there are the people of India who rejoice, decorate their houses with garlands, and give presents to their friends on this day. The people of China also celebrate this day and close their shops. The pagan god Buddha is believed to have been born on this day when the "Holy Ghost" descended on his virgin mother Maya. The great saviour and god of the Persians, Mithras, is also believed to have been born on the 25th of December long before the coming of Jesus (pbuh).
The Egyptians celebrated this day as the birth day of their great saviour Horus, the Egyptian god of light and the son of the "virgin mother" and "queen of the heavens" Isis. Osiris, god of the dead and the underworld in Egypt, the son of "the holy virgin", again was believed to have been born on the 25th of December.
The Greeks celebrated the 25th of December as the birthday of Hercules, the son of the supreme god of the Greeks, Zeus, through the mortal woman Alcmene. Bacchus, the god of wine and revelry among the Romans (known among the Greeks as Dionysus) was also born on this day.
Adonis, revered as a "dying-and-rising god" among the Greeks, miraculously was also born on the 25th of December. His worshipers held him a yearly festival representing his death and resurrection, in midsummer. The ceremonies of his birthday are recorde d to have taken place in the same cave in Bethlehem which is claimed to have been the birth place of Jesus (pbuh).
The Scandinavians celebrated the 25th of December as the birthday of their god Freyr, the son of their supreme god of the heavens, Odin.
The Romans observed this day as the birthday of the god of the sun, Natalis Solis Invicti ("Birthday of Sol the invincible"). There was great rejoicing and all shops were closed. There was illumination and public games. Presents were exchanged, and the slaves were indulged in great liberties. Remember, these are the same Romans who would later preside over the council of Nicea (325 AD.) which lead to the official Christian recognition of the "Trinity" as the "true" nature of God, and the "fact" that Jesus (pbuh) was born on the 25th of December too.
In Decline and Fall of the Roman Empire, Gibbon says: "The Roman Christians, ignorant of his (Christ's) birth, fixed the solemn festival to the 25th of December, the Brumalia, or Winter Solstice, when the Pagans annually celebrated the birth of Sol " vol. ii, p. 383.
Christmas is not the only Christian festival which was borrowed from ancient paganism and foisted upon the religion of Jesus (pbuh). There is also Easter the Feast of St. John, the Holy communion, the Annunciation of the virgin, the assumption of the virgin, and many others have their roots in ancient pagan worship.