A person obsessed with making sure that everything from public offices down to the stores you go to conform to his cultural beliefs during the Christmas Holiday season.
a Christmas Nazis will get offend with any business that even utters the word happy holidays.
Doing so will cause them to accuse you of being part of a conspiracy against their cultural/religious views. See The War on Christmas
During the Christmas Holiday Season other religions are supposed to take the back seat regardless of what the American people think.
In short these overly aggressive Religious nuts turn a Holiday that supposed to Unite people in Christian Fellowship into a Holiday that express hate toward those who practice their right to Religious Freedom. It's also a cash cow for the leaders of the Religious Right
Christmas Nazi + Conspiracy + Propaganda merchandice = Profit and discord.
Again the Christmas Season was ruined by the pro-conformity Christmas Nazi.