Luke 2:8-10 [8] And there were in the same country shepherds abiding in the field, keeping watch over their flock by night. [9] And, lo, the angel of the Lord came upon them, and the glory of the Lord shone round about them: and they were sore afraid. [10] And the angel said unto them, Fear not: for, behold, I bring you good tidings of great joy, which shall be to all people.
So, these pretty normal guys are out there doing their job.
Then are surrounded by angels and the glory of the Lord. No wonder they were scared.
I cannot even imagine what the glory of the Lord would be like, but I'm sure it would scare me a bit too. First thing the angel says is, "Fear not". Isn't it great that we don't have to fear the message from the Lord? This was great news that Jesus came down to earth to provide us a way of escape from our sin.