We are all familiar with the song, God Rest Ye Merry Gentlemen.. (let nothing you dismay)

If you research the terms that were used back THEN for some words, you would find a quite different tone to the song.

"Rest" would mean "MAKE" in our daily language.
"Merry" would mean "MIGHTY" in our language today.

SO to bring the song to understanding, it would be encouraging the Christians to stand strong...

so.. I pray, God MAKE you MIGHTY gentlemen, let nothing you dismay!