In the New Testament, the word εὐφραίνω (euphrainō) has been translated as celebrate, rejoice, glad. But only in one location, it is translated as merry, which is the famous "eat, drink and be merry" (Luke 12:19).
And He told them a parable, saying, "The land of a rich man was very productive. "And he began reasoning to himself, saying, 'What shall I do, since I have no place to store my crops?' "Then he said, 'This is what I will do: I will tear down my barns and build larger ones, and there I will store all my grain and my goods. 'And I will say to my soul, "Soul, you have many goods laid up for many years to come; take your ease, eat, drink and be merry."' "But God said to him, 'You fool! This very night your soul is required of you; and now who will own what you have prepared?' (Luk 12:16-20)
Another thing to note is the Queen appears to intentionally avoid saying "Merry Christmas" in her Christmas address. Even though many Brits have been accustomed to that phrase, the Queen still insisted every year saying "wish you a very happy Christmas".
So, is merry in fact a bad word?