"In those days a decree went out from Caesar Augustus that all the world should be enrolled." Christianity is firmly rooted in history. Unlike eastern religions that have a casual, even incidental relationship with historical events, Christianity is completely tied to the specific historical events of Jesus birth, life, death, and resurrection. Christianity is not about eternal principles. It is about an eternal person, Jesus. Over and over again the Bible connects Jesus to the specific historical times in which he lived. Caesar Augustus is a well known, well documented person in the history of the Roman Empire, and his presence in Luke's account roots us firmly at a specific time in history.
Be wary of those who want to ignore the person of Jesus in favor of his teachings. Yes, Jesus' teachings are hugely valuable. There is no greater teaching in all of human history than the Sermon on the Mount (Matthew 5-7). But if we choose to focus on Jesus' teaching rather than on Jesus himself, we miss the point. "Love God" and "Love your neighbor" -- Jesus' two great commandments -- are not a summary of Christianity. Why not? Even Jesus said "On these hang all the law and the prophets." (See Matthew 22:36-40) Exactly. The Law and the Prophets, the Old Covenant, is summed up in these two verses. But Jesus also makes clear that it is only he, himself, who fulfills that Old Covenant (See, for example, Matthew 5:17). In ourselves we strive in vain to fulfill these eternal commands to love God and love our neighbor. Jesus, at a specific time in history, took our futility on himself and did what we cannot do. First he lived a life totally devoted to God and totally available to the neighbor -- in other words, he lived in fulfillment of the specifics of the Law. More than that, however, he fulfilled the covenant of which the Law was one part. God gave the Law -- Torah -- to his people at Sinai (Exodus 19-20) in order that they might know how to have a relationship with him. This relationship was carefully bounded with regulations and sacrifices to keep the people from dishonoring God either by neglect or by easy familiarity. Jesus takes that relationship and fulfills it, as the book of Hebrews carefully explains. In Jesus' life we see what our relationship with God should be -- intimate, total devotion to a loving Father who delights in giving us abundant life through his Spirit. (By the way, this is the essence of the Trinity -- a relationship in which, through Jesus, we experience the abundant life the Father longs to give us by the presence of the Spirit in our lives. You can't explain the Trinity, you have to experience it. See Romans 8:11.) Jesus fulfills the Covenant God made with his people at Sinai. We cannot live in total love for God and our neighbor. It's beyond us. But when Jesus fulfills the covenant in his own life, death and resurrection, he sets us free to respond to him in total freedom, total devotion, total worship. In that wholehearted response to God's glorious mercy, we are turned with new eyes, new life, back into the lives of our neighbors, serving them and inviting them to come and know this holy, awesome, intimate, personal God.
All this is implied when Luke says, "In those days ..." Jesus did not come to preach eternal principles. He came, himself. The child in the manger is God's breaking in to our history, invading the reality -- not the lofty principles, but the daily details -- of our lives. He came not so we could learn how to live, but so that we might become alive. This life that the Father desires for us is not an eternal truth, but daily experience. That is why the Christian life has never been about escaping from the world, but rather being transformed by the presence of Jesus and then released back into the world.
"As the Father has sent me, so I send you" Jesus said (John 20:21). Just as he was sent into a specific time in history, a specific context, so are you. The details of your life are not an accident. Rather, God has placed you at this specific time and place in history for a reason -- to live out the abundant life he gives with these people, at this time, in this place. Even Caesar had a role to play in making God's plan a reality, though he probably didn't know it. Thank God you are living right here, right now -- and then ask him how he wants to use you!