Why do they use the term of common era?
To quote Wikipedia (which got it pretty much spot on):A range of arguments has been presented for the adoption of the Common Era notation. The label Anno Domini is almost certainly inaccurate; "scholars generally believe that Christ was born some years before A.D. 1, the historical evidence is too sketchy to allow a definitive dating."[69]It is argued that the use of BCE/CE shows sensitivity to those who use the same year numbering system as the one that originated with and is currently used by Christians, but who are not themselves Christian.[70] Former United Nations Secretary-General Kofi Annan argued, "[T]he Christian calendar no longer belongs exclusively to Christians. People of all faiths have taken to using it simply as a matter of convenience. There is so much interaction between people of different faiths and cultures - different civilizations, if you like - that some shared way of reckoning time is a necessity. And so the Christian Era has become the Common Era."[71]