The following comes from the Catholic Exchange:
It was night. The shepherds were keeping watch with their sheep in the fields.
They lived in a time of epic and empire, the greatest the world had yet seen. But here, in this land of balding hills and boulder-strewn fields, in a small town in a backwater region, about the most exciting thing these shepherds could expect was a stray wolf striking at their flock.
They were about to witness the most unexpected event in the history of the world.
First came the angel. He appeared not above them, not suspended in the air, but standing right next to them. The angel had to make way for something far greater.
Then the divine splendor of God Himself shone all around them, like a giant halo encircling a hilltop.
An angel was one thing. But this was too much for them. They were reportedly “struck with great fear.” Or, as the original ancient Greek text of the account puts it, they feared with great fear. So begins the Annunciation to the Shepherds as recorded in the Gospel of Luke, in the second chapter.
The shepherds had good reason to be afraid. Luke describes the divine splendor that shone all around them as the “glory of the Lord.” This is the same language that described the cloud that had descended upon Mt. Sinai, where Moses met with God. Then the glory of the Lord could be seen even at a distance, appearing to the Israelites far below as a “consuming fire” (Exodus 24:17). Here’s how Exodus 19 further describes the scene:
On the morning of the third day there were peals of thunder and lightning, and a heavy cloud over the mountain, and a very loud blast of the shofar, so that all the people in the camp trembled. … Now Mount Sinai was completely enveloped in smoke, because the Lord had come down upon it in fire. The smoke rose from it as though from a kiln, and the whole mountain trembled violently (Exodus 19:16, 18).
Moses spoke and God answered him in thunder (Exodus 19:19). So dangerous was the presence of God that the Israelites were ordered to come no closer than the foot of the mountain, lest they be struck dead.
As fearsome as this was, to both Moses and the Israelites, both had time to prepare for this encounter with God in His glory. Moses had conversed through the God through the burning bush. And the Israelites had seen the power of God at work in the plagues and the parting of the Red Sea.
But these shepherds on their night watch never saw it coming. The consuming fire, the cloud glowing with lighting and grumbling with thunder—they had no time to prepare for such a wonder.
But that wasn’t even the big news of the night.
The angel tells them he has “good news” of “great joy” for all of humanity. We can only imagine what is going through the shepherds’ heads at this point. Of one thing we can be assured: the angel had a captive audience. If he proclaimed something of greatness for the whole of humanity, it was pretty believable in that moment.
Then comes the news of an even more extraordinary event: For today in the city of David a savior has been born for you who is Messiah and Lord. And this will be a sign for you: you will find an infant wrapped in swaddling clothes and lying in a manger.