A certain user has repeatedly referred to classical authors as "pagan." To me personally it sounds jarring - to say the least - and, frankly speaking, totally unacceptable. I would like to find out what other members of our community think on this.
I am personally indifferent towards the word, unless it is used in an insulting tone (which I haven't seen). I can see that it has a negative tone and I certainly don't want anyone to feel uneasy on our site. I have nothing against the word when it makes a real difference, but unnecessary repetition is jarring — as with just about any word. If others feel more strongly about this word than I do, I am ready to help keep the site cleaner in that respect.
There may be cultural differences behind the tendency to use that word, including usage differences between English and a user's native language. I would assume that the word is not used with any ill intention before otherwise proven. It may well be that anyone using that word is unaware of the negative tone.
To some extent this applies to me, too: I might use "pagan" synonymously with "non-Christian" (although I admit the difference in nuance). However, I have only used the word when emphasizing non-Christianity was important, which was important for the word paganus itself, phrases with the word deus/Deus, and cursing. I hope my usage is within reasonable bounds.
I think the best course of action in a situation like this is to leave a comment which points out an issue and suggests a solution. If you would prefer them to use an alternative term ("non-Christian"?), suggest that. Make it clear that it is the negative tone of the word, not the user, that makes you uneasy. Or if you think that the word is fine when required by context but unnecessary repetition makes it harmful, state that. You can always ask whether they actually mean "non-Christian" or "classical"; it is clear that no author had Christian faith before a certain point in history. You can also suggest rephrasing in terms of positives instead of negatives, e.g. "I am more interested in Christian authors" instead of "I don't care about pagan writers". If you don't want to leave such a comment yourself for whatever reason, you can always flag a comment for moderator attention and leave it to one of us. And of course if you find a comment or any other content outright offensive, please flag it as such.
The word "pagan" is quite rare on our site, used in only 12 posts so far. The search excludes comments, and I have no data on those. The Stack Exchange Data Explorer can be used to study them, and an anonymous helper composed a SEDE query for comments containing a specific word on our site. The query can easily be modified for other similar searches, should the need arise.
A word has little meaning without context. Did you perhaps encounter this word in a certain specific situation where it seemed reprehensible to you? I am speaking only for my naïve self here, but my immediate response is one of surprise: I can't think of a context in which I would object to the word pagan.
In academic literature, it is in my experience the normal word to use for non-Christians in late Antiquity. I remember studying the matter of the Victory Altar (Christians such as bishop Ambrose of Milan wanted it removed from the Curia), and pagan was the normal word to refer to those authors and politicians who wanted to keep it there (such as the senator Symmachus). Similarly, in overviews of the literature of late Antiquity, one commonly distinguishes between pagan authors such as Macrobius and Christians like Augustine.
An arbitrary example, search results from the Oxford Handbook of Late Antiquity: https://books.google.com/books?id=KEYSDAAAQBAJ&pg=PA91&dq=oxford+companion+antiquity&sa=X&ved=0ahUKEwiW4anu7e_aAhXC2aQKHaSED1MQ6AEIJzAA#v=onepage&q=pagan&f=false