Before Common Era

Historical events like coronations, natural disasters, wars, and the like cannot be demonstrated by logical necessity to have happened.  Maybe they did, and maybe they did not, as long as they are logically possible; there is still testimonial, hearsay evidence that certain events did take place—even if the documentation is from an eyewitness who made no assumptions and did not distort any information, it is still hearsay for future readers.  The epistemology of history is seldom broached in a rationalistic way, but something that is more likely to come up in conversation is the terminology of dividing historical eras.

On a very broad scale, the timeline of recorded history is separated into BCE and CE, or "Before Common Era" and "Common Era".  Becoming more widely used in the 1900s, these words are the more neutral replacement for BC and AD, which have very distinctively Christian origins.  Now, someone who uses the abbreviations BC or AD, as well as the full phrases "Before Christ" and "Anno Domini" (the "year of the Lord"), does not have to be a Christian.  It is not as if use of these phrases in any way necessitates that a person has ideological respect for Christianity, much less explicit commitment to it.  The words were just the norm.

What does and does not follow from the way that BCE and CE are used?  Ironically, while new terms are substituted for the conventional ones, the Before Common Era/Common Era system still keeps a general historical division entailed by Christian philosophy.  The words are different, but not the ultimate timeline itself.  Both BC and BCE have the same reference point for what years are before Christ or the Common Era, and both AD and CE have the same reference point for what years start with or are after Christ's birth, also referred to as the Common Era.  2016 AD is the same as 2016 CE, though even the genuine historical evidence for the life and death (as Biblically asserted) of Jesus does not point to his birth occuring in the exact year that starts the "Common Era".

The very likely historical presence of Christ was nonetheless so impactful that it eventually led to even the predominant secular timeline being assigned terms that correspond with the approximated period before and after his birth.  This impact is of no small significance, nor is the prominence and influence of Christianity, either in its truly Biblical sense or its asinine distortions like evangelicalism and Catholicism, limited to the way many people have referenced the calendar and timeline of human history.  Again, cultural visibility and direct/indirect acknowledgement of that visibility by using the word AD still does not mean someone is expressing affirmation of, commitment to, or even a positive disposition towards Christianity.

In spite of the writings of people like Josephus and Tacitus mentioning the historical Jesus, people who have used BC and AD in communication about history might not even think it probable that any such person lived in the first century.  In no way is cultural impact in the future alone a proof that someone lived, died, and resurrected roughly two thousand years ago, but even if it was—and historical documentation could never be the same as a logically necessary truth, so this is only to show what would follow from this impossible thing—relying on the terms BC and AD is not personal assent to this, similarly to how someone can like the aesthetic of cross-related jewelry and still have no philosophical allegiance to or personal interest in Christianity.