@Nick

Yeah, I think "his" and "shen" are just typos, someone put this faulty phrase online and now the whole world is just copying it. I guess that most Chinese, especially when they're rather familiar with Pinyin than with Wade-Giles wouldn't understand this phrase.

@Kinson

What do you mean by that I'm wrong? I didn't transliterate the line. I found it like this online. I know that "恭贺新年并祝圣诞“ should be written as "gong he xin nian bing zhu sheng dan" in Pinyin.

I found the phrase "Kung his hsin nien bing chu shen tan" like this online. It's not my invention. You can find it here for example http://xmasfun.com/Merry-Christmas-In-Other-Languages.aspx or here http://www.yantri.net/news/christmas_newyear.html. Or look at this pic: http://www.thegummybear.com/2015/12/05/kung-his-hsin-nien-bing-chu-shen-tan/. There it says that it's Cantonese.

So, the thing is: on multiple websites this phrase is promoted as the translation of "Merry Christmas" in Chinese. But in fact, my theory is that the transliteration (faulty Wade-Giles, instead of Pinyin how it is used in China) and the translation wrong (wrong order of Christmas and new year).

My money is on that being someone's faulty romanization, as the previous commenter said.

:) As a teacher in Taiwan in the 1990s, I taught a class called "Introducing Taiwan in English" for tourism personnel. I made proper use of  romanization systems a major part of that class. 

Hi Miriam, do you think "his" is simply a misspelling of "hsi"? I know the romanization doesn't match the characters, but outside the mainland where hanyu pinyin is not learned in school (e.g. in Taiwan), romanization is notoriously faulty.