Think of archaeologists in 1000 years from now come over documents with 100 different time concepts.
B.C. and A.D. suffice, anything else is political nonsense or anti-religious propaganda.
[1] https://en.wikipedia.org/wiki/Year_zero [2] https://en.wikipedia.org/wiki/ISO_8601#Years
In Sweden we have been discussing about what type of signs should we put up to warn for nuclear waste. Will people in thousand of years be able to understand and decide the warnings?
Same with time concepts, the future must have a sporting chance to understand what we where talking about.
A days-as-dots representation[1] has one day precision at a thousand years BP, and since accuracy of a day or week is often possible, it was actually an issue. Wrestling with "everyone has their own odd calendar" was a pain.
[1] "History shown with days as dots - so centuries fit on a screen"'s "Days-as-dots demo" was basically an exploratory UX test piece: http://www.clarifyscience.info/part/QEt9x . The Google Books and Google Newspapers links are regrettably rotted - it was great fun to click on random days in the 1800's and 1900's and read random newspapers of that day. :/ The inset NY Tribune from the Library of Congress still works. My fuzzy impression is the google newspapers database is simply unavailable now?
You should read up on the history of the Common Era to correct your parochial misconceptions.
i think this is misleading if not a bit ethnocentric (or rather religiocentric?). the islamic, jewish and hindi calendars all have different numbered years, and presumably most others.
to turn this around, the fixation on AD and rejection of other proposals could be described as christian supremacist 'propaganda'. it 'suffices' because it accommodates to your comfort and privilege.