Israel is located between the Mediterranean Sea and the Arabian Desert on the same latitude as that of Korea, so the climate of both regions is similar. One difference is that Israel has a shorter spring and autumn, and longer summer and winter than those in Korea, and that it is characterized by a huge daily temperature range. That is because it is situated in the region where the Mediterranean climate meets the subtropical climate.
Winter is the rainy season in Israel, so it rains a lot and the temperature falls off. So, people move their sheep into the sheep pen at least by October so that they can go through winter there. Therefore, it is hard to keep watching over the flock of sheep in the fields at night in midwinter, December.
The birth of Jesus
When we read the Bible, we can find out that the shepherds who were keeping watch over their flocks in the fields at night heard the news about the birth of Jesus from an angel.
Lk 2:3-12 And everyone went to his own town to register. So Joseph also went up from the town of Nazareth in Galilee to Judea, to Bethlehem the town of David, because he belonged to the house and line of David. He went there to register with Mary, who was pledged to be married to him and was expecting a child. While they were there, the time came for the baby to be born, and she gave birth to her firstborn, a son. She wrapped him in cloths and placed him in a manger, because there was no room for them in the inn. And there were shepherds living out in the fields nearby, keeping watch over their flocks at night. An angel of the Lord appeared to them, and the glory of the Lord shone around them, and they were terrified. But the angel said to them, “Do not be afraid. I bring you good news of great joy that will be for all the people. Today in the town of David a Savior has been born to you; he is Christ the Lord. This will be a sign to you: You will find a baby wrapped in cloths and lying in a manger.”
The fact that the shepherds kept watch over their flocks in the field at night on the day when Jesus was born is the circumstantial evidence proving that Jesus was not born in the cold season. In other words, December 25 is not the birthday of Jesus. Then, why do many churches commemorate December 25 as the birthday of Jesus even though He was not born on that day?
The origin of Christmas
As Christianity was introduced into Rome and it was approved by Emperor Constantine in 313 A.D. and became the state religion of the Roman Empire, Christians felt the need to celebrate Jesus’ birthday. However, they could not find the date from the Bible, so people brought up several dates that they estimated as the birthday of Jesus.
Until the early 3rd century, nothing was decided about the birthday of Jesus and people celebrated it on any day in March, May or November. Then December 25 came up for the first time by Hippolytus, one of the fathers of the Rome Church. Without any exact foundation, he made a presumption that the Virgin Mary conceived Jesus on March 25 and insisted that it was certain that Jesus was born on December 25. At that time, his insistence did not catch any attention.
Meanwhile, the church in Jerusalem in the east appointed one day among early January, as the birthday of Jesus and as the day when Jesus was baptized; and they celebrated each of them in Bethlehem and in the Jordan River. As it was hard for people to travel to the two places, which are separated by more than 30 km [19 miles] away, in a day, they came to complain about it.