Yeah, there was a thread, but it got derailed into a large and tiresome religion argument.
At least symbolically, A.D. and B.C. can stand for nothing other than what we use it for. The support for this line of reasoning comes primarily from etymological dissection of the script (references to a monotheistic God, etc.), the unedited Heaven element (Lightning in the American version, altered due to Nintendo's censorship) as well as something no one seemed to notice but is unreasonably prominent, which means a bunch of people need to see an eye doctor; the GIANT OMFG IMPOSSIBLE TO MISS pair of crosses on the doors of Manoria Cathedral in the PSX ending with Crono and Marle getting married. The "Real World Influences" article is in error where it states that no crosses are present in the series, but so many other things go on here that it's a comparatively insignificant detail. As someone on Chronicles pointed out, this may not in fact be Christianity as we know it, but rather a sort of clone of Christianity, such as the Diablo universe's religion of Zakarum; as one would expect from such a title, the story is situated around angels, demons, and thoroughly Western religious concepts. The Church of Zakarum uses a gothic cross as its symbol and preaches the Visions of Akarat, the human incarnation of the Light (*coughJesusclonecough*). Several of the obtainable pieces of Guardian armor and weaponry are distinctly Roman in appearance, as well, not to mention the image on their gold coins (extracted from the CT manual) -- unmistakably that of a Roman centurion.
In my experience with the subject, people seem to get pissed off at it because they assume that if A.D. and B.C. actually mean Anno Domini and Before Christ, then Christianity is fact in Chrono; this is a highly fallacious leap of logic often perpetrated by those who for one reason or another dislike Christianity, failing to realize the abundance of other religious influences in the series. SquareEnix resides in Japan, after all, and in Japan less than 1% of the population is Christian; most are Buddhists, and several Eastern concepts, such as a living world, are present in the series, as well as several other Square games, most notably Final Fantasy VII. Indeed, the contemporary B.C. & A.D. approach to Chrono would be flawless save for that statistic. Even animes with decidedly Christian content, such as Neon Genesis Evangelion, are not worked on by Christians; Hideaki Anno, the mastermind behind Eva, stated that none of the staff who worked on it were Christian. Yet the series is replete with Christian imagery, including the Angels, Adam and Lilith, the Instrumentality Project, and the infamous cross-shaped explosions ensuing from Angel missiles, as well as the souls in End of Evangelion. Coincidentally, the artistic-looking diagram shown in Eva's intro sequence is that of the Sephirotic System, aka the Tree of Life in Jewish Kabbalistic tradition.
If you're thinking "OMFG SEPHIROTH" you're right. Interestingly, I learned that before I ever actually played FF7.
In any case, we use this dating system in the real world, and a good many people don't think it's anything vaguely approaching factual; this has a high probability of being the case on Crono's Earth. Why people sometimes fail to see this is puzzling.
As far as the writers being lazy, I highly doubt this, considering they put forth the time and effort to work out the main storyline.
