Linus explains to Charlie Brown what Christmas is all about:
And there were shepherds living out in the fields nearby, keeping watch over their flocks at night. An angel of the Lord stood before them, and the glory of the Lord shone around them, and they were greatly afraid. Then the angel said to them, "Do not be afraid, for behold, I bring you good tidings of great joy which will be to all people. For there is born to you this day in the city of David a Savior, who is Christ the Lord. Luke 2:8-11
According to Strong's Greek & Hebrew Dictionary the words in verse 10 for "all people" are "pas laos" means "everyone" or "all men." If the angel wanted to say that the Savior was for just a select group he could have said that Jesus' birth for a certain select few, but he didn't, he said the Savior was for all people.
The Christmas message is this, the Savior, was and is for all men. For kings and shepherds, wise men and ignorant men, Jews and Gentiles, and even a thief on a cross some 33 years later.
The Significance of the Christian Feast of Michaelmas, the Jewish Feast of Tabernacles, and December 25th
The Bible does not tell us the actual date of Christ’s birth and the early church did not celebrate “Christmas”, certainly not as we know it.
Dr. Henry Morris, founder of the Institute for Creation Research, wrote an interesting article "When God Became Man" (1) explaining how both the fall date and the December date are significant in regard to the birth of Jesus.
A feast called the Feast of Michaelmas was popular in the Middle Ages and according to Dr. Morris the feast was celebrated on September 29th in observance of the angel, Michael, who may have been the main angel among the heavenly host sent to announce the birth of Jesus to the shepherds.
Michaelmas was celebrated several days before the Jewish Feast of Tabernacles which was observed “each fall in gratitude for the annual harvest, with each family dwelling for a time in a tent, or "tabernacle.” When John wrote that "the Word was made flesh, and dwelt among us", he did not use the usual Greek word for "dwell." Instead, he said, literally, that the Word (that is, the Creator) "tabernacled" among us for a time...”
Dr. Morris then went on to explain that the actual incarnation of Jesus would have been “when He created a body for Himself and took up His residence in Mary's womb” nine months prior to His actual birth and not the birth itself.
“…that brings us back to December 25 again! The actual number of days between the two dates is 278, which is the ideal period of human gestation…How appropriate it would be for Him to enter the world right at the season of darkest and longest night, for He would come as "the light of the world"…”
Adding to the importance of December 25th "the original significance of December 25 is that it was a well-known festival day celebrating the annual return of the sun. December 21 is the winter solstice (shortest day of the year and thus a key date on the calendar), and December 25 is the first day that ancients could clearly note that the days were definitely getting longer and the sunlight was returning."
(2) And so on or about December 25th the Son of God came to the world at a dark time to bring light to the world.
When Jesus was eight days old His parents took him to the temple to present Him to the Lord. At that time there was an old man at the temple named Simeon who had been told by the Holy Spirit that he would not die until he had seen the Messiah. The Bible tells us:
Simeon took him in his arms and praised God, saying: "Sovereign Lord, as you have promised, you now dismiss your servant in peace. For my eyes have seen your salvation, which you have prepared in the sight of all people, a lightfor revelation to the Gentiles and for glory to your people Israel." Luke 2:28-32
Several centuries prior to the birth of Jesus Isaiah in the Old Testament Scriptures prophesied:
The people walking in darkness have seen a great light; on those living in the land of darkness a light has dawned... For to us a child is born, to us a son is given, and the government will be on his shoulders. And he will be called Wonderful Counselor, Mighty God, Everlasting Father, Prince of Peace. Isaiah 9:2;6
And during His ministry Jesus spoke about being "the light of the world":
When Jesus spoke again to the people, he said, "I am the light of the world. Whoever follows me will never walk in darkness, but will have the light of life." John 8:12
Then Jesus cried out, "...I have come into the world as a light, so that no one who believes in me should stay in darkness." John 12:44-46
1. Morris, H. 2008. When God Became Man. Act & Facts. 37 (12): 10-12. http://www.icr.org/article/4283/
2. ChristianAnswers.net, What are some of the most common misconceptions about Jesus Christ's birth? http://www.christiananswers.
The Life and Times of Jesus the Messiah
Alfred Edersheim M.A.Oxon., D.D. Ph.D.(1825-1889)
CHAPTER VI.: THE NATIVITY OF JESUS THE MESSIAH.
...But as we pass from the sacred gloom of the cave out into the night, its sky all aglow with starry brightness, its loneliness is peopled, and its silence made vocal from heaven. There is nothing now to conceal, but much to reveal, though the manner of it would seem strangely incongruous to Jewish thinking. And yet Jewish tradition may here prove both illustrative and helpful. That the Messiah was to be born in Bethlehem, was a settled conviction. Equally so was the belief, that He was to be revealed from Migdal Eder, ‘the tower of the flock.’ This Migdal Eder was not the watchtower for the ordinary flocks which pastured on the barren sheepground beyond Bethlehem, but lay close to the town, on the road to Jerusalem. A passage in the Mishnah* leads to the conclusion, that the flocks, which pastured there, were destined for Temple-sacrifices,  and, accordingly, that the shepherds, who watched over them, were not ordinary shepherds. The latter were under the ban of Rabbinism,  on account of their necessary isolation from religious ordinances, and their manner of life, which rendered strict legal observance unlikely, if not absolutely impossible. The same Mishnic passage also leads us to infer, that these flocks lay out all the year round, since they are spoken of as in the fields thirty days before the Passover - that is, in the month of February, when in Palestine the average rainfall is nearly greatest.  Thus, Jewish tradition in some dim manner apprehended the first revelation of the Messiah from that Migdal Eder, where shepherds watched the Temple-flocks all the year round. Of the deep symbolic significance of such a coincidence, it is needless to speak....
*The Mishnah (Hebrew "repetition") is a major source of rabbinic Judaism's religious texts. It is the first recording of the oral law of the Jewish people, as championed by the Pharisees, and is considered the first work of Rabbinic Judaism.
 In fact the Mishnah (Baba K. vii. 7) expressly forbids the keeping of flocks throughout the land of Israel, except in the wilderness - and the only flocks otherwise kept, would be those for the Temple-services (Baba K. 80 a).
 This disposes of an inapt quotation (from Delitzsch) by Dr. Geikie. No one could imagine, that the Talmudic passages in question could apply to such shepherds as these.
Full text version: www.ccel.org/ccel/edersheim/lifetimes.txt Full HTML version: www.ccel.org/ccel/edersheim/lifetimes.toc.html
The following is a similar discussion from the author/speaker Frank Peretti in 2014:
Christmas Timeline of the Biblical Account
The Magi and their Heaven-Shattering News
An explanation of why tradition always portrays the wise men as three kings who traveled on camels, even though Matthew's gospel doesn't say so.
From Answers In Genesis:
What Was the Christmas Star?
The Star of Bethlehem
Born in a Barn (Stable)?
Was Mary Really a Virgin, and How Important Is It?
Magi, Kings, or Wise Men?
We Three Kings
A Matter of Time
The Humble Bethlehem
The Day Christ Was Born
Is biblical Christmas story true? Is Jesus Christ for real
When did the Luke 2 census occur?
What are some of the most common misconceptions about Jesus Christ's birth?
What Is The Real Meaning Of Christmas?
What was the Star of Bethlehem?
If Christ's miracles really happened, why weren't they reported by historians?
President Harry S. Truman's Christmas address December 24, 1949