@KalebOutWest
Indeed, Christmas is NOT the "birthday" of Jesus, but the celebration of his birth, let's make this distinction. The celebration of his birth does not have to coincide with the actual day of his birth, this was the case of the Queen Elizabeth II:
https://www.rmg.co.uk/stories/topics/why-did-queen-have-two-birthdays
As we do not know the exact date of Christ’s birth, the date of December 25 for Christmas may have been arbitrary. The Church could have chosen another date on which to celebrate the birth of Christ. One reason December 25 may have been deemed suitable is its proximity to the winter solstice. After that date the days start to become longer, and thus it is at the beginning of a season of light entering the world (cf. John 1:5). The summer solstice—after which the days start to get shorter—falls near June 24, on which the Church celebrates the birth of John the Baptist, who declared of Christ, “He must increase, but I must decrease” (John 3:30).
In response to the claim that Christmas was originally a pagan holiday, this is a misconception popularized by American puritan Protestants who were hostile to Catholicism and fabricated the "Sol Invictus" myth. Ancient sources do not support this claim. Unfortunately, contemporary Jesuits, in their defense of the faith, aprioristically argued that this instead proved the legitimacy of Christianity, which - as is well documented - baptized the "seeds of the word" found in paganism. However, this was not the case here. Pagan emperors, following the example of Kim Jong-il and Stalin, attempted to appropriate the already existing Christian festival... unsuccessfully.
The date of Jesus' birth was not "decided upon," but celebrated in Rome as early as the 3rd century, well before the artificially established festival of "Sol Invictus." (This is why the introduction of "Sol Invictus" was unsuccessful, even among pagans.)
The birth date of Mithras is also often cited. This is a fallacy propagated by the "Zeitgeist" movement; original sources should be consulted to understand when and how Mithras was celebrated. This is akin to claiming expertise in wilderness survival and bushcraft based solely on watching the Rambo movies! Additionally, the Hellenized cult of Mithras is later than Christianity. Also, it is a common sense truth in religious studies that formal similarities may either represent completely different meanings or have no genetic relationship between two religions. Furthermore, it is demonstrable that, partly due to chronological reasons, homologous religious phenomena were incorporated into the Mithras cult in competition with Christianity, making it contrived and unviable. It was about as widespread as any modern occult sect.
As for the actual date of Jesus' birth, Gustav Teres attempted to determine this using astronomical methods in his book "The Bible and Astronomy" (2000). The date of celebration is related to the theory of "integral age." According to tradition, prophets (messengers of God) die on the day of their conception or birth. Thus, Jesus, who according to Christian belief is the prototype of the prophets, was crucified on Nisan 14, which was identified with the Greek Artemision 14. In Egypt, this was dated to April 6, 30 AD, and in the West to March 25, 33 AD. (Note: in these two years, the Jewish Passover coincided with the Sabbath.) This led to the erroneous dating of Jesus' birth. Based on the mystique of 33 years, whereas he might have been around 40 years old (even the image on the Shroud of Turin depicts such a man), it is believed he was born around 7 BC, corresponding to the Hellenic acme (prime of life).
Therefore, Christmas did not precisely coincide with the solstice (only Stalin's falsified birthday did), but was determined by adding nine months to the date of his death. This resulted in December 25 in Rome and January 6 in Alexandria, as both places chose different years (30 and 33, respectively) when Jewish Passover and Nisan 14 aligned.
Christian teachings are not fundamentally affected by the exact date of Jesus' birth or the date of the celebration. The pagan festival that can be demonstrably proven is the wheat consecration procession. Today, its significance is mostly as a tourist attraction. However, the inclusive Catholic perspective views paganism not as inherently "ab ovo" evil but as preserving fragments of the original revelation.
Since the Watchtower literature and JW identity rely heavily on Hislop's theory, it is worthwhile to outline this question.
"Paul taught that holiness cannot be mixed with impurity."
The verses cited in this regard only serve as a legitimate argument against syncretism or false irenicism, but not against inculturation.
This double standard is also interesting, since while Christmas etc. JWs refers to the "pagan origin", while in other cases they admitted that it does not matter what the origin of a pagan is, pagan or not pagan, but:
"In such matters, what generally is influential is whether a practice is now linked to false religion." (w92 9/1 pp. 30-31)
"Admittedly, true Christians today are not preoccupied with the roots and possible ancient religious connections of every practice or custom..." (w98 10/15 pp. 30-31)
... but of some, they are :-)
"Even if it were a fact that pagans first used wedding rings, would that rule such out for Christians? Not necessarily. Many of today’s articles of clothing and aspects of life originated in pagan lands. The present time divisions of hours, minutes and seconds are based on an early Babylonian system. Yet, there is no objection to a Christian’s using these time divisions, for one’s doing so does not involve carrying on false religious practices. [...]
Really, the question is not so much whether wedding rings were first used by pagans but whether they were originally used as part of false religious practices and still retain such religious significance." (w72 1/15 pp. 63-64)
"Still, all kinds of objects, designs, and practices have, at some time or place, been given a false interpretation or have been linked with unscriptural teachings. Trees have been worshiped, the heart shape has been viewed as sacred, and incense has been used in pagan ceremonies. Does this mean that a Christian must never use incense, have trees in any decoration, or wear heart-shaped jewelry? That is not a valid conclusion.
A genuine Christian should consider: Would following a custom indicate to others that I have adopted unscriptural beliefs or practices? The time period and location could influence the answer. A custom (or design) might have had a false religious meaning millenniums ago or might have such today in a distant land. But without going into time-consuming investigation, ask yourself: ‘What is the common view where I live?’—Compare 1 Corinthians 10:25-29." (w91 10/15 pp. 30-31)
So why can't the SAME standard be used to judge ALL customs?
By the way, this "pagan orign stuff is bad" ideology ironically tempted Catholicism as well, and it didn't exactly work in the Church's favor:
https://en.wikipedia.org/wiki/Chinese_Rites_controversy
In short: When the Jesuits and the Franciscans began their mission in China, they tried to use the beliefs of the Chinese with the purpose of an apologetic bridge, for example they translated the word "God" as Shàngdì.
The Dominicans said that this was wrong, since Shàngdì was already the name of the supreme deity in the old Chinese pantheon, so it was of "pagan origin", so a term for God that was not yet "contaminated" should be used. They defended themselves by saying that this is essentially the same as by linking it with the "unknown god" as described in Biblical passage of Acts 17:23–31. The Dominicans complained to the Pope, citing that such translation may associate the Christian God to Chinese polytheism.
Unfortunately, the Pope at the time listened to them, and the result was the banning of Christian missions by the emperor. Without this stupid "pagan influence" fallacy, there is a good chance that China would be a Christian country today, and history would be very different.
In the 20th century, the Pope revoked this ban, but Chinese Catholics still call God Tiānzhǔ.
The point is: Inculturation is a legitimate missionary tool, as long as it does not result in an essential compromise in its content of the Christian religion.
By the way, as far as I know, the very first historical source that claims that Christmas falls on December 25th because they wanted to override Sol Invictus is from the 12th century and is attributed to Dionysius bar Salibi. So there is not a single contemporary source that would have claimed something similar, the first speculation about it is almost a thousand years later. In the twelfth century, the Syriac theologian Dionysius Bar-Salibi wrote that December 25 was established in the West as the feast of Christ’s Nativity to coincide with the pagan Roman celebration of the Invincible Sun. He wrote:
"It was a custom of the Pagans to celebrate on the same 25 December the birthday of the Sun, at which they kindled lights in token of festivity. In these solemnities and revelries the Christians also took part. Accordingly when the doctors of the Church perceived that the Christians had a leaning to this festival, they took counsel and resolved that the true Nativity should be solemnised on that day."
This concept became popular in the West particularly in the eighteenth and nineteenth centuries. More recent scholarship has shown that Christmas had been observed for years before Emperor Aurelian established the pagan festival in AD 274.
More recent studies have shown that many of the holiday’s modern trappings do reflect "pagan customs" borrowed much later, as Christianity expanded into northern and western Europe. The Christmas tree, for example, has been linked with late medieval druidic practices. This has only encouraged modern audiences to assume that the date, too, must be pagan.
https://www.biblicalarchaeology.org/daily/people-cultures-in-the-bible/jesus-historical-jesus/how-december-25-became-christmas/
