The 'C' in BC reflects what event makes the era 'common', 'common era' is meaningless on its own. Whether or not you're religious, the birth of Christ is a conv

The 'C' in BC reflects what event makes the era 'common', 'common era' is meaningless on its own. Whether or not you're religious, the birth of Christ is a convenient starting point for the western ('Gregorian' - who is Gregory?) calendar.