Peace on Earth, good will to all.
Merry Christmas.
kai epi ghs eirhnh ev anthrwpois eudokias
The correct translation is most likely:
"And on earth, peace to men of good will" not "peace on earth, good will to men."
Eudokias is plural in the verse and is most likely an adjectival form modifying the plural anthrwpois (men).
To interpret "good will" as a substantive noun here, it would be a plural substantive which is not really found in Greek.