According to Luke 2:4, 39, Mary and Joseph lived in Nazareth. They traveled about 128 kilometers from Nazareth to Bethlehem. Bible scholars determined that their route from Nazareth was south along the flatlands of the Jordan River, then west over the hills surrounding Jerusalem, and then into Bethlehem. It was about 8 to 10 days of travel, or more considering that Mary was pregnant.
There are many reasons that can answer the question: why Bethlehem? Let me just cite two Old Testament prophecies.
The first prophecy is the one given by the Prophet Micah 700 years before the birth of Jesus. Micah 5:2 says, “But you, Bethlehem Ephrathah, though you are small among the clans of Judah, out of you will come for me one who will be ruler over Israel, whose origins are from of old, from ancient times.” This prophecy states that the Messiah will be from Bethlehem.
The census conducted by the Roman Empire required the Jews to go back to their hometown. Both Joseph and Mary traced their roots to Bethlehem. One can only marvel with this divine providence: the Roman census became a way to fulfill an ancient prophecy.
The second prophecy is that the Messiah will come from the line of David. Bethlehem is the birthplace of David. Here are two Old Testament passages:
Psalm 132:11 says, The Lord swore an oath to David, a sure oath he will not revoke: “One of your own descendants I will place on your throne.” It is not a mere man or woman who made this oath. It was God himself who swore an oath.
The Prophet Jeremiah confirmed this oath of God in Jeremiah 23:5-6. Once again, it was God who said this — “The days are coming,” declares the Lord, “when I will raise up for David a righteous Branch, a King who will reign wisely and do what is just and right in the land. In his days Judah will be saved and Israel will live in safety. This is the name by which he will be called: The Lord Our Righteous Savior.”
Aside from being the place where David was born, Bethlehem was also the place where Prophet Samuel crowned David king of Israel. Ruth and Boaz, great-grandparents of David were also married in Bethlehem.
Romans 1:2-4 affirms the fulfilment of the oath of God to David — “God promised this Good News long ago through his prophets in the holy Scriptures. The Good News is about his Son. In his earthly life he was born into King David’s family line, and he was shown to be the Son of God when he was raised from the dead by the power of the Holy Spirit. He is Jesus Christ our Lord.”
Indeed Jesus who is from the line of David, born in Bethlehem, is the Messiah, our Lord and Savior.