Eight.
X, the Greek letter Chi, the first letter of “Christ,” has long (and not always disrespectfully) been used as an abbreviation for “Christ” in words like “Christian” and “Christmas.”
I have never in my life heard “Xian” or “Xtian” used respectfully.
While not particularly worshipful, “Xian” and “Xtian” are used as a short method of typing by any number of posters, just as Xmas is used throughout society. It is no more “frankly” offensive than Xmas and even if you do not enjoy seeing it, it hardly reaches the level of deliberate insult that Heeb does.
However, you have ignored the point that the OP actually returned to the thread to acknowledge that he may have overstated his case. Jumping on another poster (for a rather silly disagreement over abbreviations) after that poster has already withdraw more substantive criticisms is not considered good form.
Current Urban Dictionary polls on xtian:
the two neutral definitions have overwhelming support; the two denigrating definitions have overwhelming opposition; the one claim that is rather ambiguous has mild support.
Similar results for xian.
Try not to take unnecessary insult where it is not required.
I don’t really view Xian as offensive although I do think the OP and several others on this forum use “Xian” and “Xmas” offensively or to be intentionally disrespectful. It is telling many of the most loudly self-proclaiming atheists insist on using the “X” prefix. Xian isn’t quite as normal as Xmas, but Xmas actually has some history of being used in that manner in a completely non-offensive way.
I’ll use Xmas sometimes myself, but anytime I see someone deliberately use Xian and Xmas repeatedly and never use the full-length normal English words it’s usually a sign that the person has an axe to grind.
Or an “X” to grind? 
Good post, Martin! If I see a Letter to the Editor complaining about the “Xmas” in a headline of the sort “Xmas Caroler Hit by Bus,” I mentally conclude that the writer is someone looking for a place to be offended. The Chi-Rho monogram for Jesus, XP, often written with the P rising from the X like a shepherd’s crook, is older than the English language.
At the same time, I believe that you’re correct that PRR does it intentionally to irritate, as a part of his scoffing at “irrational” beliefs. I personally am trying to emulate my Lord and not allow it to anger me. It’s nowhere near as objectionable, in my view, as classifying all beliefs as identical to fairies dancing in the garden and then smiting them root and branch with the bludgeon of one’s supposed wit. Or of insisting that because some Christians take a literal view of the Bible, those who share with scholars a different view are somehow less Christian – or less Xian; would that be xian?
Besides, I always wanted to be a Chinese city! 
(And, intriguingly, one where a large part of the populace believes in the God of Abraham!)
You can be offended by the Xtian if you like.
Jesus is offended that you have not sold everything you own and given it to the poor.
Assuming facts not in evidence. Don26 may be an absolute atheist who simply believes that “Xian” has a particular rude meaning and wants prr to stop employing it.
(While unlikely, it IS possible.)
On the other hand, there is really no particular reason for you to be launching personal digs in this Forum. It does not move the discussion forward and it creates unnecessary friction.
Point taken. I could have made the same point without getting personal and I apologize.
tomndebb you have been in this thread, so you know the kind of position Don26 has taken is one to which I take particular umbrage.
Don26 I invite you to give your opinion in the thread linked above.
First, the Bill of Rights goes on about enjoining Congress from enacting laws that prohibit or establish the free practice of religion. The separation clause is does not actually exist as US code, although Jefferson’s Danbury Letter evokes the phrase, and states an elegant position on the need for the separation of church and state. And there is that bit in a treaty that states quite forcefully that the US was in no way founded specifically as a Christian nation. And there is the blanket prohibition of the use of tests of faith in determining eligibility for government posts. Then there’s the Lemon test, which essentially rules unconstitutional any law posed solely or substantially for religious purposes.
However, for good or for ill, religion has always been a part of public life, since religion is a part of the peoples’ personal and public lives. An absolute segregation of government and religion has never been in place.
It is essential that we oppose the abusive mixing of government and religion, but the personal musings of am incumbent President at the funeral of a deceased former President is not in and of itself representative of a religious test, or of the establishment of religion.