In those days Caesar Augustus issued a decree that a census should be taken of the entire Roman world. 2 This was the first census that took place while Quirinius was governor of Syria. 3 And everyone went to their own town to register.
4 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. (Luke 2:1-4)
Luke spends a very long time on the events surrounding Christ’s birth. Although Luke did not use chapters and verses (they were a later addition – first incorporated in the 13th century), at 80 verses, Luke 1 is a “whopper”. Christ has been mentioned but he is not born in Luke 1. This adds to the suspense, the intrigue, the drama, the story. We could be forgiven for forgetting about the backdrop of the Roman Empire. Apart from the introduction addressed to Theophilus (1:1-4), the chapter is mainly centred on the salvation history of Israel. This new section, however, suddenly parachutes us back into contemporary events within the historical context of the Roman Empire.
Largely for positive and necessary reasons, people have always moved between regions and nations. Although censuses remain a bit tedious, they remain important for recording demographics. The situation was no different at the beginning of the Roman Empire. Augustus was the first Roman emperor, and the period was hailed in Rome as a new “golden age” of peace. Officials were appointed around the expanding Roman Empire, even in Syria, where Quirinius was in charge. One major census, where everyone had to go and register at their place of birth, was decreed around the time of Jesus’ birth.
Enter a certain Joseph from Nazareth in Galilee who had to go back to Bethlehem. The narrative zooms in on him; warning sirens sound again when Luke reminds us that he was “from the house and line of David” (v.4; cf. 1:27). Joseph has to make this 100km journey because of a routine, bureaucratic census. It seems mad, even boring. Yet, God is at work: fulfilling and shaping history. God can work through worldly events, no matter how trivial or momentous they are. This reminds us to remember those who hold power, the Augusti and Quirinii of our day, and to pray for them. When writing to the churches in Rome, Paul exhorts them to submit to authorities (Romans 13:1-7). Naturally, there are limits to this, but prayer and positive witness to the authorities is important. If God could use a census, who knows how He might use the course of historical events?
 There are some historical questions about the timing of the census, which it is not possible to address here. I found this article quite informative though: http://crossexamined.org/really-census-time-caesar-augustus/