" 'Merry Yom Kippur!' I have no idea what you mean." -- Candy Wright
It was a sarcastic remark. Jews do not wish each other a merry Yom Kippur, because for Jews, Yom Kippur is the most solemn day of the year, as Good Friday is for Christians.
"I have not seen what the POTUS actually said regarding Good Friday" -- Candy Wright
Trump didn't "say" it. As the original poster wrote, Trump Tweeted in all caps, "HAPPY GOOD FRIDAY TO ALL!"
"Yep. That's what the President of the United States tweeted out earlier today." -- MisterPicture