It's a common abbreviation, that is all. It is an abbreviation of the 'Chi-Rho' symbol which was itself an abbreviation used by early Christians (it is the first two Greek letters of the term 'Christ', which is a Greek word meaning 'the anointed one') . Do not take it as an insult an many are so wont to do owing to ignorance.
The correct abbreviation is XP (chi-rho), being the first two letters of the word 'ΧΡΙΣΤΟΣ (Christos)', which you have explained yourself. When you type 'xians', you are actually abbreviating what is already an abbreviation and to say that it is a commonly accepted word is ignorant.
FALSE! Christians and Jews are clearly cited in the Koran as "Unbelievers" The only people who are noted as believers in the Koran, are Muslims. Christians and Jews are also noted as "people of the book", but that doesn't mean they are rated as believers. This is basic.
And why would anybody have respect for a cult (masquerading as a religion) that advocates mass genocidal murder (Koran 8:12, ....9:5....9:123, et al), wife beating (Koran 4:34), pedophilia (Koran 65:4) slavery (Koran 4:36....4:92....23:5-6....24:31/58 et al) and other vile, immoral and illegal (under US law) things ?
People of the Book/Scripture (Arabic: أهل الكتاب ′Ahl al-Kitāb) is an Islamic term referring to Jews, Christians, and Sabians and sometimes applied to members of other religions such as Zoroastrians. It is also used in Judaism to refer to the Jewish people and by members of some Christian denominations to refer to themselves.
The Quran uses the term in reference to Jews, Christians and Sabians in a variety of contexts, from religious polemics to passages emphasizing community of faith between those who possess monotheistic scriptures.
No foundation therefore remains for any theory or practice that leads to discrimination between man and man or people and people, so far as their human dignity and the rights flowing from it are concerned.
The Church reproves, as foreign to the mind of Christ, any discrimination against men or harassment of them because of their race, color, condition of life, or religion. On the contrary, following in the footsteps of the holy Apostles Peter and Paul, this sacred synod ardently implores the Christian faithful to "maintain good fellowship among the nations" (1 Peter 2:12), and, if possible, to live for their part in peace with all men,(14) so that they may truly be sons of the Father who is in heaven.(15)
Well if you can't prove it, then you are left with, and have, nothing but a hunch.
As for me having to prove the Jesus Christ existed, HA HA HA, pardon me but the pause really required a hearty laugh. I hope you know that historical figures are known to exist, by all the history that has been written about them, by people they associated with. Can you prove Napoleon existed ? Alexander the Great ? Plato ? Moses ? Mohammed ? Julius Caesar ? Nero ? Of course. Jesus is even more provable , because thousands of people, in various locations attested to having witnessed his miracles. The largest religion in the history of mankind didn't come from nothing.