Why did Origen oppose birthdays?
In part it was because it was a pagan custom and in part it was because there was no ancient Hebrew tradition of celebrating one’s birthday on a yearly anniversary basis. He had a great respect for the Jewish people.
Like other Early Church Fathers, Origen taught doctrine and defended Christianity against heresies. In doing this, their sole appeal for authority was Scripture. (Source)
Origen of Alexandria is well known for writing against pagan practices and customs, as well a honouring the ancient Scriptural customs of the Jewish people. For example Origen credits Jews with a special talent for exorcising demons (Against Celsus, book 4).
Certainly Origen was aware of the first century AD, Josephus writings that stated "the law does not permit us to make festivals at the births of our children, and thereby afford occasion of drinking to excess" (Against Apion, II.26).
Of the two birthday celebrations mentioned in Scriptures, both of them were accompanied with bloodshed!
Origen, wrote over two centuries after the death of Our Lord Jesus Christ. Origen was very passionate about preaching about the Book of Leviticus. In his Homilies on Leviticus, speaking on the aspect of birth, Origen states the following:
. . . not one from all the saints is found to have celebrated a festive day or a great feast on the day of his birth. No one is found to have had joy on the day of the birth of his son or daughter. Only sinners rejoice over this kind of birthday. For indeed we find in the Old Testament Pharaoh, king of Egypt, celebrating the day of his birth with a festival, and in the New Testament, Herod. However both of them stained the festival of his birth by shedding human blood. . . . But the saints not only do not celebrate a festival on their birth days, but, filled with the Holy Spirit, they curse that day, (after the example of Job, Jeremiah and David).
Your first link source states the following:
In their essay titled "Birthdays, Jewishly," Lisa Farber Miller and Sandra Widener point out that the Encyclopedia Judaica is very blunt on this topic:
"The celebration of birthdays is unknown in traditional Jewish ritual."
Did Early Christians Celebrate Birthdays? NO, only the Pagans did!
Yes this may be true, but there were birthdays that were traditionally celebrated amongst the Jews. Exceptions to this were when a child was weaned, his first hair cut and of course his Bar Miẓwah. In fact, the Jewish Encyclopedia explain this quite well and it acknowledges that the traces of celebrating Christ’s birth has its origin within the Early Church.
There are no positive data in the Bible or in rabbinical literature concerning birthday festivals among the ancient Jews. This silence on the subject is, however, no warrant for the conclusion that the Jews altogether abstained from following a custom which was general among the Egyptians (Gen. xl. 20), Persians (Herodotus i. 133), Syrians, and Greeks. Even if not common among the people, yet kings and princes probably practised it, following the custom of their heathen contemporaries. Birthday festivals were not considered by the Rabbis as "ḥukkot ha-goyim" (customs of the heathen; see Maimonides, Yad ha-Ḥazaḳh, 'Akkum we-Ḥuḳotehem, xi. 12), although Lightfoot held a contrary opinion ("Horæ Hebr." on Matt. xiv. 6).
A close study of the Biblical text shows that the Bible is not altogether wanting in references to the subject; for, while it lacks positive accounts, it contains passages from which it may be inferred that the custom of remembering birthday anniversaries was not wholly unknown among the Jews. "The day of our king" (Hosea vii. 5), on which the princes made the king sick with bottles of wine, and the king himself "stretched out his hand with scorners," alludes more probably to a birthday festival than to a solemn occasion, such as the anniversary of his installation, which would have been observed with more decorum (see Josephus, "Ant." xv. 9, § 6).
Birthdays might not have been celebrated by the common people with great solemnity, yet they did not pass wholly unnoticed, and were remembered by congratulations, as in modern times. Jeremiah not only cursed the day of his birth, but wished that it should not be blessed (Jer. xx. 14), as though such had been the custom.
It is said of Job, "and he cursed his day" (Job iii. 1). The emphatic and determining expression "his day" implies the idea that he, like everybody else, had a certain day of the year singled out for a certain purpose, which we learn further was the anniversary of his birth.
Weaning on Second Birthday
The second or third birthday of a child whose coming into the world was very much desired by his parents was usually made the occasion of a feast, because the child was then weaned, and had consequently passed the dangerous and uncertain stage of infancy. Abraham made a great feast on the day Isaac was weaned (Gen. xxi. 8). This occurred, according to Rashi, at the expiration of twenty-four months. Bishop Ely ("Holy Bible Com." l.c. on the passage) says: "By comparing I Sam. it would seem that this was very probably a religious feast." Hannah postponed the yearly family feast at Shiloh until she had weaned Samuel, in order to celebrate his birthday at the same time (I Sam. i. 23, 24). According to Rashi and Midr. R. Samuel, l.c., this also occurred at the end of twenty-four months. Yet from II Chron. xxxi. 16 it may be inferred that Samuel was weaned at the end of his third year; for only from that age were children admitted to the service of the Temple.
In Post-Biblical Times
Two instances of birthday celebrations are mentioned in post-Biblical literature, from which it may be assumed that this was customary in the Herodian family. They used to celebrate birthdays with great pomp, and in the same manner as the Egyptian kings had done more than 2,000 years earlier (Gen. xl. 20), by extensive public entertainments, which were made the occasions of granting favors to friends and pardons to those in disgrace. Agrippa I. solemnized his birthday anniversary by entertaining his subjects with a festival, and decreed the recall of his banished general Silas, which recall, by the way, the latter stubbornly declined (Josephus, "Ant." xix. 7, § 1). Herod the Tetrarch celebrated his birthday with a great feast, at which the daughter of Herodias danced before the guests, the king promising "to give her whatsoever she would ask" (Matt. xiv. 6).
The Bar Miẓwah
The Jewish people in general may have had reasons to avoid feasting on birthdays in the times of the Tannaim and Amoraim: first, because they had been at one time grievously offended on such festivals (according to II Macc. vi. 7, the Jews were forced, in the time of Antiochus, to eat of the sacrifices which were offered "in the day of the king's birth every month"); secondly, because no "Talmid ḥakam" would attend as a guest at such a feast, since the Rabbis condemn the Talmid ḥakam who partakes of a meal or feast which is not a "se'udat miẓwah" (commendable meal). And to the son of him who frequented feasts were applied opprobrious epithets, such as "son of an oven-heater," "son of a market-dancer," etc. Since the fifteenth century (Löw, "Lebensalter," p. 210) the thirteenth birthday of a boy has been made the occasion of a family feast because it coincides with his religious majority (Bar Miẓwah).
Special Birthdays of Scholars.
In modern times the widely spread custom of celebrating some particular birthday of a great man by a banquet or by some literary production has enriched Jewish literature with many gems of Hebrew learningand poetry. Jewish scholars of great renown have become the recipients of marks of deference and homage on the part of their friends and admirers on their seventieth or eightieth or ninetieth birthday by the publication of a jubilee-book, to which scholars from far and near have contributed some of their best work.
About the meaning of of the Mishnah, which seems to correspond with ἡμέρα γενεσεώς (LXX., Gen. xl. 20), some doubts have been raised because, by the side of ("birthday of the king") mention is also made of ("the day of birth and the day of death"). In the Babylonian Talmud ('Ab. Zarah 10a) the decision is reached in favor of as meaning "the day of coronation." It is accepted by Maimonides (see Commentary to the Mishnah, and Yad ha-Ḥazaḳah, 'Akkum we-Ḥukotehem, ix. 5). The glossary "Kesef Mishneh," ad loc., thinks that Maimonides may have read ("assembly") for. Rasḥi explains as equivalent to "the birthday of the king"; while the Talmud Yerushalmi ('Ab. Zarah i. 39) explains as "birthday." This agrees with the use made of the word in many instances (Gen. R. lxxxviii.; Ex. R. xv.; Yer. R. H. iii. 8; Yalḳ., Job. 584; Compare Rashi, Gen. xl. 20). Graetz (in "M. G. Y." 230) is of the opinion that means the day of death of the king.
All these difficulties and differences may be obviated if be explained as indicating Christian festivals of the early Church. By may be understood the Nativity, or Christmas, and by Easter, or the Resurrection. Cave (in "Primitive Christianity," part 1, vii. 194, cited in McClintock and Strong's "Cyclopedia," s.v. "Christmas ") traces the observance of Christmas to the second century, about the time of the emperor Commodus. According to David Ganz ("Ẓemaḥ David," i., year 3881), Commodus reigned 183-185, at the time of Rabbi Meïr of the Mishnah, who counted those days as legal holidays. - Birthday
The 2nd-century patristic writer St. Irenaeus of Lyon regarded the conception of Jesus as 25 March coinciding with the Passion. Tertullian believed also that March 25th was Christ’s Conception and Death. Thus a Conception leads to a December 25th birthday!
Yes, the Scriptures do not say anything about celebrating the Birth of Christ as we commonly say as Christmas, but the Sacred Scriptures do not directly forbid it either.
Tertullian held that Christ’s conception and death were on March 25th, exactly nine months prior to December 25th.
But where did he get this idea from, that the crucifixion was on the 8th day before the kalends of April, March 25?
There is a lunar calendar on the statue of Hippolytus in the Vatican Library. Apparently a note within this indicates the “Passion of Christ” was on Friday March 25.
Tertullian, Adversus Judaeos 8:18:
Quae passio Christi [huius exterminium] intra tempora LXX ebdomadarum perfecta est sub Tiberio Caesare, consulibus Rubellio Gemino et Rufio Gemino mense Martio temporibus paschae, die octavo Kalendarum Aprilium, die primo azymorum quo agnum occiderunt ad vesperam, sicut a Moyse fuerat praeceptum.
And the suffering of this “extermination” was perfected within the times of the lxx hebdomads, under Tiberius Caesar, in the consulate of Rubellius Geminus and Fufius Geminus, in the month of March, at the times of the passover, on the eighth day before the calends of April, on the first day of unleavened bread, on which they slew the lamb at even, just as had been enjoined by Moses. - March 25 – the date of the annunciation, the crucifixion, and the origin of December 25 as the date of Christmas?
If the birth of Christ was not celebrated in the Early Church, at least the foundations were obviously there, even if Origen, being in Egypt was unaware of this.
Wikipedia has an interesting note about the Festival of Dies Natalis Solis Invicti:
Festival of Dies Natalis Solis Invicti
The Philocalian calendar of AD 354, part VI, gives a festival of natalpubeis invicti on 25 December. There is limited evidence that this festival was celebrated before the mid-4th century. The same Philocalian calendar, part VIII, also mentions the birth of Jesus Christ, stating that the "Lord Jesus Christ was born eight days before the calends of January" (that is, on December 25).
Since the 12th century, there have been theories that the near-solstice date of 25 December for Christmas was selected because it was the date of the festival of dies natalis solis invicti, but historians of late antiquity make no mention of this, and others speculate Aurelian chose December 25 to shadow early Christian celebrations already on the rise.
Aurelian also built a new temple for Sol, which was dedicated on 25 December 274, and brought the total number of temples for the god in Rome to four.
Since I cannot interrogate Origen to discern exactly what he meant by, “the saints not only do not celebrate a festival on their birth days, but, filled with the Holy Spirit, they curse that day”, for saints were all born as sinners, stained with original sin*. Scriptures also declares that one himself who is born whether male or female is not "clean from filth although his life is of one day.” And that you may know that there is something great in this and such that it has not come from the thought to any of the saints; not one from all the saints is found to have celebrated a festive day or a great feast on the day of his birth.
Yet, Jesus was like men in all things yet without sin. Thus the the theological underlined basis for celebrating Christ’s birthday can be seen here. To say that ”others believing in Christmas is not relevant, they must be later and disconnected with the religion”, in not congruent with understanding of the theology of Jesus’s conception and birth, from the Church’s point of view. Whether or not December 25th is the actual birthday of Jesus, is not important, what the Church is doing is celebrating the birth of the God-man in his human nature and making a statement to those who deny his incarnation and two natures and being united to the Father and the Holy Spirit within the Most Holy Trinity.
Besides, Origen has never been canonized by either the Orthodox or Catholic Churches.
The following articles may be of interest to some:
John Chrysostom - Homily on the Date of Christmas ”This day was known from the beginning to those in the West: now it has been brought to us and before the passing of many years, has swiftly shot up, bearing such fruit as you now see – the precincts full and the church packed with the crowd who have gathered together.”
Was the date of Jesus' birthday chosen from a pagan celebration? ”Around 200 C.E. Tertullian of Carthage reported the calculation that the 14th of Nisan (the day of the crucifixion according to the Gospel of John) in the year Jesus died was equivalent to March 25 in the Roman (solar) calendar. March 25 is, of course, nine months before December 25; it was later recognized as the Feast of the Annunciation—the commemoration of Jesus’ conception. Thus, Jesus was believed to have been conceived and crucified on the same day of the year. Exactly nine months later, Jesus was born, on December 25.”
Patrologiae cursus completus, Pages 491-508 contain Origen’s complete Homily 8 on Leviticus in Latin.