Which system do you prefer to use when identifying past eras?
Kenneth G. Wilson (1923-). The Columbia Guide to Standard American English. 1993.
A.D., B.C., (A.)C.E., B.C.E.
A.D. (or AD) is an abbreviation for anno Domini, "[in] the year of our Lord," for dates after the year conventionally numbered 1, and B.C. (or BC) stands for "before Christ," for dates before that year. A.D. appears either before or after the number of the year (A.D. 1066 or 1066 A.D.), although conservative use has long preferred before only; B.C. always follows the number of the year (55 B.C.). The use of the periods is a matter of style.
Recently B.C.E., meaning either "before the Christian era" or more frequently "before the common era," has had some champions, but Edited English seems only rarely to have adopted it thus far. (A.)C.E., "(after the) common (or Christian) era," seems to have prospered even less, perhaps because some regard it as slighting Christianity (which is ironic, given that both alternatives were proposed to avoid the possible disrespect implied by the more popular terms). Common era (C.E.) itself needs a good deal of further justification, in view of its clearly Christian numbering. Most conservatives still prefer A.D. and B.C. Best advice: don't use B.C.E., C.E., or A.C.E. to replace B.C. and A.D. without translating the new terms for the very large number of readers who will not understand them. Note too that if we do end by casting aside the A.D./B.C. convention, almost certainly some will argue that we ought to cast aside as well the conventional numbering system itself, given its Christian basis. At present the familiar Latin/English convention has the considerable advantage of being the one most of the world's written languages use in communicating with cultures other than their own. SeeDates