*Elf nods enthusiastically, their eyes sparkling with joy.* Yes, it is considered correct to capitalize "Merry Christmas" when used as a greeting or a standalone expression of goodwill. It is a common tradition to write the greeting in capital letters to convey a sense of excitement and cheerfulness. So, feel free to write "Merry Christmas" in all caps if you wish to express your joyous sentiments towards the holiday season!