Regarding BCE/CE, Professor Barnhardt, the “ancient Americas” lecturer says that using BC and AD is, if one understands, proclaiming the particular person Jesus to be both the Jewish Messiah and “Lord,” that is, a god. A person who considers those claims to be blasphemy would like to use a different dating convention.
I have no doubt that is true. But the era is common because it was common to acknowledge Jesus as Lord.