In every piece I am writing and will publish in the future on Judaism's relationship with xianity, historical dissertations, refutation of missionary material, and so on, a pattern emerges: I never write the full name of the religion I am discussing or the name of the man worshipped by its followers. It can come as puzzling or even insulting to readers. It's not the intention. Please, let me explain:
In Judaism, we are forbidden to write or pronounce the name of idols. To be blunt, the worship of Yoshke constitutes idol worship in the eyes of Judaism, at least for Jews. I know and understand that the typical xian answer to this is, 'Of course not! We are monotheists; in fact, we believe in the same one you do!' The thing is, it's true from your perspective but not ours. Remember that you yourself protest the very same way we do when Muslims claim that you worship the same one they do!
It is essential to mention, however, that while xianity is 100% considered to be idol worship for a Jew and therefore entirely prohibited, many deciders of Jewish Law have proclaimed that as far as non-Jews are concerned, this is something called shittuf, association, and does not fall under the category of idol worship. Practically, this differentiation means nothing for any Jewish person and does not diminish the weight of the interdiction one iota. Non-Jews are permitted to eat non-kosher food, but that doesn't make it any more kosher for a Jew to eat it. In the same way, if a Jew worships an idol, he loses his share in, and is cut off from, the World to Come.
Standing at Sinai, the entire Jewish Nation heard the First of the Ten Commandments from the mouth of G-d: "I am the L-rd your G-d who took you out of Egypt, out of the house of bondage; You Shall Have No Other god Before Me." G-d is the one who took us out of Egypt, and He is who we worship. We have no concept of G-d coming to earth in an earthly body anywhere in Judaism, any abrogation of the law or any other form of supersessionism. Mashiach, the Messiah, will be a man of flesh and blood, born of a mother and a father, and his role will be similar to the task that Moshe took upon himself when he led us out of Egypt. Just as a man led us out of Egypt under G-d's supervision, a man will lead us out of the current exile under G-d's direction and bring all of humanity to the recognition of the one G-d.
The Greek term "christos" means "anointed." It ascribes to Yoshke the title of Mashiach (ch" vs). As such, referring to the religion with its full name implies that this is the religion of Mashiach G-d forbid and something utterly contrary to our beliefs. This is why we do not use that term either.
It's not a question of being petty, it's not a question of mocking your beliefs, it's a question of staying true to ours. I have a lot of respect for xians. I believe you are wrong as far as your beliefs go, but I'm sure you'll forgive me as you equally think I am wrong, after all. However, ultimately we both profess claim in one G-d, and I am far more interested in your ethical behavior than our theological differences.
Ok, fine, but what about writing G-d? What's wrong with the ‘o’?
Here's an entire article about why, but it suffices to say
Following the Torah's instruction to "obliterate the name" of idolatry in the Land of Israel, the Torah warns us not to do the same to G-d. We thus learn that there is a prohibition to erase G‑d's name. Writing G‑d's name could lead to erasing or disrespecting G‑d's name, as will be discussed.