And isn't it wonderful that we remind ourselves of the great god Thor every Thursday? Jesus gets a reference for the year, but Thor is greater because he gets referenced 52 times every year.
actually, we use ? BCE now, which mean before common era, and we use CE instead of ad, which means common era, so we don't reference jesus when we mention the year.
The Gregorian calendar was only invented in the 6th century AD (along with the concept "AD") Before that there was the Julian Calendar where the first month of the year was June