Sometimes we sing familiar Christian songs so many times that we tend to sing the words without giving a lot of thought to the meaning. The Christmas songs especially have many lines that are deeply meaningful to our faith, and that express very vividly what happened that first Christmas.
This past Sunday we sang “Silent Night” at our church. When we sang the words “shepherds quake at the sight” it really impacted me. The Bible says that the shepherds were “terrified” when an angel appeared before them to tell them the good news about the birth of Jesus. How frightened they must have been! I would have been scared too, and so would you.
Maybe we all should pledge to listen more closely to the words we sing. When we really hear the message, it makes all the difference in the world.
“An angel of the Lord appeared to them, and the glory of the Lord shone around them, and they were terrified.”—Luke 2:9.
Jesustrek 
That was just a word choice to make it rhyme in English. The German original says “Hirten erst kundgemacht”, which means “Shepherds first made it known”. In that case, it’s to rhyme with “Stille nacht, helige nacht” (Silent night, holy night).
Finding the right balance between theology and musicality is kind of a fluid dynamic.