Yom Kippur is a time of reflection and atonement, so a celebratory “Happy Yom Kippur” doesn’t ring true.
Don't say 'Happy Yom Kippur': How to greet someone observing the Jewish Day of Atonement
Yom Kippur is a time of reflection and atonement, so a celebratory “Happy Yom Kippur” doesn’t ring true.