Olympiad dating system
As former UN General Secretary Kofi Annan put it in a statement marking the turn of the millennium: The Christian calendar no longer belongs exclusively to Christians.' For some, these are fighting words: the Southern Baptist Convention resolved, also in 2000, to resist the 'revisionism' implicit in the CE/BCEsystem and to retain AD 'as a reminder to those in this secular age ... The AD/BC chronology is not so ancient as some proponents suppose; nor is the CE/BCE system so recent.
For the first five centuries of their religion, Christians marked time according to local conventions, usually from the legendary foundation of Rome (753 BC), or from the Diocletian reforms (284 AD).
According to the Muslim lunar calendar, dating from Muhammad's Hijra (flight or emigration) from Mecca, it is now ah 1430.
However, it only gained universal acceptance among Christians in the 15th century.
Meanwhile, in 1615 Johannes Kepler used the phrase anno aerae nostrae vulgaris (in the year of our common era) in an astronomical table and 'Common Era' or its equivalents are known, if rare, in 18th-century works such as the Encyclopaedia Britannica of 1797.
Only then will our historical practice be truly common.
A final argument: the AD/BC system is factually wrong.