"Now in those days a decree went out from Caesar Augustus, that a census should be taken of all the inhabited earth. This was the census taken while Quirinius was governor of Syria. And everyone was on his way to register for the census, each to his own city. Joseph also went up from Galilee, from the city of David, which is called Bethlehem, because he was of the house and family of David, in order to register along with Mary, who was engaged to him, and was with child. While they were there, the days were completed for her to give birth" (Luke 2:1-6). It is commonly assumed (and implied by the Greek wording) that this census was linked to a taxation; the familiar rendering of the KJV reads, "That all the world should be taxed. ... And this taxing was first made. ... And all went to be taxed."
This particular tax mattered. In fact, it was pivotal in the history of the world - not merely because it was the first of its kind, but on a far grander level, because it set up the conditions necessary for the birth of the Messiah. Approximately 700 years before the birth of Christ, God had foretold, "But as for you, Bethlehem Ephrathah, too little to be among the clans of Judah, from you One will go forth for Me to be ruler in Israel. His goings forth are from long ago, from the days of eternity" (Micah 5:2). Mary, who was carrying the Child, and Joseph her fiancée lived in Nazareth, seventy miles away. The actual connection by road likely required over ninety miles of travel. At a walking pace of three miles per hour, the trip would have required five six-hour days.
Why would a young couple travel for a week under the travel conditions of that era to get to a place that had little connection to them, particularly at a time when the woman was very pregnant? They wouldn't, unless they were compelled. God needed them in Bethlehem in order to fulfill prophecy, so He compelled them by directing a powerful world leader to enact a tax that was both unwelcome in its reality and inconvenient in its implementation.
God knew when the time was right. In modern medicine, doctors can still only estimate the time of birth, but God knew Mary's due date precisely. God knew when the Messiah's forerunner, John the Baptist, would be born and would start his ministry. God knew when the world would be at relative peace, unified by language and transportation, making conditions advantageous for the spread of the gospel. God knew when the Jewish people would be looking expectantly for their Messiah, having already faced captivity and now being under oppressors again. God knew when the age of law would have clearly demonstrated its ineffectiveness, as the Jews had gone through periods of unbelief and empty ritual, always unable to keep the law's demands.
Ultimately, God knew precisely the time line that He Himself had laid out in Daniel 9, and He directed all these aspects of history - personal, Jewish, and world - to come together at the right time. "But when the fullness of the time came, God sent forth His Son, born of a woman, born under the Law, so that He might redeem those who were under the Law, that we might receive the adoption as sons" (Galatians 4:4). God had a very definite and precise plan, and He brought that plan to fruition by whispering into the mind of Caesar Augustus that he ought to institute a world-wide census and that he should facilitate that census by causing people to have to travel to designated locations within certain time constraints.
Under the sovereign design of God, a tax changed the world forever by serving as the framework for the birth of the Savior. Joseph, Mary, and the others of their day probably didn't like the tax any more than people of today like the taxes required of them. Joseph and Mary found their compulsory trip uncomfortable and inconvenient, but God accomplished through that taxation and through that trip something beyond what the people of that time could understand.
The same sovereign God continues today to use uncomfortable and inconvenient things for His purposes. He continues to work through (and even initiate) the actions of governments and other leaders. When God has a plan to accomplish, nothing can stop Him. Furthermore, everyone and everything yields to His superintendence. God is in control!
"The LORD of hosts has sworn saying, 'Surely, just as I have intended so it has happened, and just as I have planned so it will stand'" (Isaiah 14:24).