The alternative acronyms are neologisms created specifically out of anti-Christian sentiment.
If y'all were operating in good faith, these would catch the same level of attention:
- Sabbatical, originating from Sabbath, a Judeo-Christian day of rest,
- The use of "karma", "zen", and "avatar" as terms and concepts, which come mostly from eastern religion,
- The use of "kosher", "mazel tov", and "golem" outside religious contexts due to their Judaic roots,
- and the use of "assassin", from a group of Shiite militants during the Crusades.
Of course, none of these catch the sort of attention that BC and AD do, because this is an example of explicitly anti-Christian thought, word, and deed. If you are particularly averse to it as opposed to other religions, that is your personal bigotry to work through, not ours to placate.