According to Brother Abu Mussab Wajdi Akkari, who looks like he's just out of diapers, telling someone "Merry Christmas" is as evil, shirk and kufr as it gets. Yes, those two little words "Merry Christmas" are worse than alcohol, fornication and killing someone.
There are some who don't take such a bah, humbug attitude towards it, like the first Imam in this video, but the second one, Dr. Zakir Naik, is just as anti-Merry Christmas as the silly young brother in the above video, though not quite so extreme.
Lebanese born Akkari now lives in Saudi Arabia, where I'm sure he feels quite at home with all the other Wahhabi lunatics.
Ho, ho, ho.