Chrsitological Timeology de-Converter

Picture this: you find yourself engaged in a particularly interesting, intellectual debate, perhaps at a dinner party( or on the train). When out of nowhere, someone mentions an historical event, but you are positive they have the date wrong. You're about to correct them, but then catch yourself as you have almost uttered old-timey chronology parlance, doing so would make you look a damned fool in the eyes of this learned company!

Fret not, stranger!! As the As yet Undecided team of mathematicians and time-doctors bring you the Christological Timeologoy de-Converter! No longer will you be the pariah of social discussions when you inadvertently use antiquated B.C/A.D dating conventions.