Luke tells us that the shepherds were sent an invitation from heaven to go and visit the new-born baby. This was a great privilege that was given to them. Usually shepherds were not highly respected in the community and were not likely to receive an invitation to any event. But here they are, given the most incredible invitation ever, and it was delivered by an angel.
Moreover, they realised that the birth of this infant made heaven glad. They heard the angels singing about it. When was the last time a choir of angels had sung about what was taking place on the earth? Job tells us that the morning stars sang for joy at the creation, and here they are singing, we might say, at the dawning of the new creation now that the Messiah has come as a baby.
So away they went to see the baby and they came back singing. They did not sing along with the angels because they had not yet seen the baby. Luke tells us that some people had gathered round the manger and the shepherds told them what they had seen (Luke 2:18). Having gone, they then returned praising God for what they had heard and seen. In a very short time, they had become witnesses about Jesus to others and worshippers of God for sending his Son.
The shepherds were different from the civil authorities. Paul reminds us in Galatians that Jesus was born in the fullness of time, which is another way of saying that he was born at the right moment. Yet the Old Testament had said that he would be born in Bethlehem. Something had to happen to cause Joseph and Mary to travel to Bethlehem for the birth, and Luke tells us that the person responsible for this decision was Caesar Augustus, the Roman Emperor himself. He had his reasons for the decision he made, which was to do with registration, but behind the scenes God had his reason, which was that Mary would give birth to Jesus in Bethlehem.
No message ever went to Caesar Augustus that Jesus had been born in Bethlehem, although it is possible that one day a minor official may have received a scroll mentioning that Joseph and Mary had travelled to Bethlehem from Nazareth and registered in obedience to his decision. Yet the obvious lesson is that God is in charge of all things and when he wishes he can cause the powerful of the earth to do what he wants even although they have no idea that they are furthering the progress of his kingdom. And he can use their decisions to bring blessings to those at the other end of the social scale, as he did with the shepherds.