There are some important clues we should understand. They begin with the miraculous birth of John the Baptist, who was Jesus' second cousin, and the "voice in the wilderness" who was to announce the coming of the Messiah.
Notice what the Bible says about this great event: ""There was in the days of Herod, the king of Judaea, a certain priest named Zacharias, of the course of Abia: and his wife was of the daughters of Aaron, and her name was Elisabeth.
"And they were both righteous before God, walking in all the commandments and ordinances of the Lord blameless.
"And they had no child, because that Elisabeth was barren, and they both were now well stricken in years.
"And it came to pass, that while he executed the priest's office before God in the order of his course,
"According to the custom of the priest's office, his lot was to burn incense when he went into the temple of the Lord.
"And the whole multitude of the people were praying without at the time of incense.
"And there appeared unto him an angel of the Lord standing on the right side of the altar of incense.
"And when Zacharias saw him, he was troubled, and fear fell upon him.
"But the angel said unto him, Fear not, Zacharias: for thy prayer is heard; and thy wife Elisabeth shall bear thee a son, and thou shalt call his name John.
"And thou shalt have joy and gladness; and many shall rejoice at his birth.
"For he shall be great in the sight of the Lord, and shall drink neither wine nor strong drink; and he shall be filled with the Holy Ghost, even from his mother's womb.
"And many of the children of Israel shall he turn to the Lord their God.
"And he shall go before him in the spirit and power of Elias, to turn the hearts of the fathers to the children, and the disobedient to the wisdom of the just; to make ready a people prepared for the Lord.
"And Zacharias said unto the angel, Whereby shall I know this? for I am an old man, and my wife well stricken in years.
"And the angel answering said unto him, I am Gabriel, that stand in the presence of God; and am sent to speak unto thee, and to show thee these glad tidings.
"And, behold, thou shalt be dumb, and not able to speak, until the day that these things shall be performed, because thou believest not my words, which shall be fulfilled in their season.
"And the people waited for Zacharias, and marvelled that he tarried so long in the temple.
"And when he came out, he could not speak unto them: and they perceived that he had seen a vision in the temple: for he beckoned unto them, and remained speechless.
"And it came to pass, that, as soon as the days of his ministration were accomplished, he departed to his own house" (Luke 1:5-23).
Zacharias served during the "course of Abia," or the EIGHTH of the priestly courses (meaning their assigned times of service) in the Temple (see 1 Chronicles 24:10). This took place twice each year. Each time of service, or "course" changed each week, commencing on the Sabbath. The reckoning commenced on the 22nd day of Tisri or Tehanim, which was the eighth day of the Feast of Tabernacles, the "Last Great Day."
Remember that the courses served together at the three great feasts. The dates for the twice-yearly ministrations of Abia fall on the 12th to the 18th of Chisleu (our December 6th to the 12th), and from the 12th to the 18th of Sivan, or our June 13th to the 19th.
Therefore, the announcement about the CONCEPTION OF JOHN occurred somewhere between our June 13th to the 19th in 5 BC!
Old Zacharias' course ended on the Sabbath, our June 20th, which would have been a Sabbath. Therefore, he could not have journeyed to his home on that day, but would have left on the 21st, our Sunday. He lived "in the hill country of Judaea," about 30 miles away. Easily, this was a two day journey for an elderly man, putting him home late on the 22nd of Sivan, or our June 23rd. Therefore, the miraculous conception of John HAD TO TAKE PLACE somewhere on June 23rd or 24th of 5 BC!
To this day in England, the "Day of the Nativity of John the Baptist" is June 24th! In reality, it is not the date of his BIRTH, but the date of his conception!
Elizabeth and Mary were first cousins. Therefore, John the Baptist and Jesus were second cousins. John was conceived on the 7th of Nisan, corresponding to our June 23rd or 24th, in 5 BC.
Six months later, on the first day of the Jewish month Tebeth, which corresponds to our December 25th, 5 BC, Jesus Christ was begotten. Nine months later, when the shepherds were still "abiding in the fields by night," Christ was born in Bethlehem on our September 29th, which fell on the FIRST DAY OF THE FEAST OF TABERNACLES!"
Bullinger's Companion Bible says, "The fact of the birth of our Lord having been revealed to the shepherds by the Archangel Michael on the 15th of Tisri, corresponding to September 29th, 4 BC—the FIRST DAY OF THE FEAST OF TABERNACLES—must have been known to believers in the Apostolic age. But the `mystery of iniquity' which was already working in Paul's day (2 Thessalonians 2:7) quickly enshrouded this and the other great fact of the day of the Lord's `begetting' on the first day of the Jewish month Tebeth, corresponding to December 25th, 5 BC, as well as other events connected with His sojourn on earth, in a rising mist of obscurity in which they have ever since been lost.
"The earliest allusion to December 25th as the date for the Nativity is found in the Stromata of Clement of Alexandria, about the beginning of the Third Century AD.
"That `Christmas' was a pagan festival long before the time of our Lord is beyond doubt. In Egypt, Horus, the son of Isis (queen of heaven), was born about the time of the winter solstice. By the time of the early part of the fourth century AD, the real reason for observing Christmas as the date for the miraculous `begetting' of Matthew 1:18 and `the Word becoming flesh' of John 1:14 had been lost sight of...If, however, we realize that the centre of gravity, so to speak, of what we call the Incarnation is the Incarnation itself—the wondrous fact of the Divine `begetting' when `the Word became flesh'—and that this is to be associated with December 25th, instead of March—as for 1,600 years Christendom has been led to believe—then `Christmas' will be seen in quite another light..."
"The announcement to the shepherds by the Archangel Michael marked the birth of our Lord. John 1:14 is read as though `the Word became flesh, and dwelt among us' were one and the same thing, whereas, they are two clauses. The paragraph should read thus: `And the Word became flesh; [Gr. Ho logos sarx egeneto.] `And tabernacled with [or among] us,' [Gr. Kai eskenosen en hemin].
"The word tabernacled here [preserved in the RV margin] receives beautiful significance from the knowledge that the `Lord of glory' was `found in fashion as a man,' and thus tabernacling in human flesh. And in turn it shows in equally beautiful significance that our Lord was born on the FIRST DAY OF THE GREAT JEWISH FEAST OF TABERNACLES, vis. The 15th of Tisri, corresponding to September 29th, 4 BC [modern reckoning].
"The circumcision of our Lord took place therefore on the eighth day, the last day of the Feast, `The Great Day of the Feast' of John 7:37" (ibid. Appendix 179, emphasis mine).
Christ is the central figure of all the annual Sabbaths, or Feasts, of God. He is the Passover Lamb. He is the "living Bread" depicted by the unleavened bread of the "Days of Unleavened Bread" following the Passover. He is the FIRST of the "firstfruits" depicted by the "Feast of Sabbaths," or the "Feast of the Firstfruits," which was celebrated by counting until the 50th [the word "Pentecost" is Greek for "fiftieth"] day following the wave sheaf offering during the Days of Unleavened Bread. He is the soon-coming King of kings and Lord of lords, whose arrival is heralded by the blowing of the great trumpet of the archangel on the "Feast of Trumpets." He is our "Atonement" pictured by the fast day of Atonement.
The feast of temporary booths, or kiosks, or shanties, or huts, or "tabernacles," portrays our total transitory nature; our impermanence on this earth during our short physical life span.
In a shadowy type, it also looks forward to our eventual inheritance of our permanent, spirit body, when we inherit the Kingdom of God.
Notice, "Now this I say, brethren, that flesh and blood [this means you and me, in our physical bodies] cannot inherit the kingdom of God; neither doth corruption inherit incorruption.
"Behold, I show you a mystery; We shall not all sleep [die: the Bible continually uses profound "sleep" as a type of death], but we shall all be changed,
"In a moment, in the twinkling of an eye, at the last trump: for the trumpet shall sound, and the dead shall be raised incorruptible, and we shall be changed.
"For this corruptible must put on incorruption, and this mortal must put on immortality" (1 Corinthians 15:50-53).
Read the entire 15th chapter of 1 Corinthians. Paul explains how the physical body is to decay, but that, in the resurrection, a new spirit body is given to the dead in Christ, or the living in Christ, who are changed, in a "twinkling of an eye."
We celebrate the Birth of Jesus.
Does it matter if it's the exact same day as 2000+ years ago? The fact is, we celebrate, as least as much as we are permitted to, thanks to the misinterpretation of "separation of church and state."
Good will. That means kindness and a genuine concern for one's fellow humans. What do you do, besides criticize your fellow man, to celebrate the Birth of Jesus?
May God bless you!