Ebbie, I recall the argument many decades ago and 4 BC seems the best date to mark Jesus' birth. There have been other calendar changes over the centuries that affect the calendar we use today.

"September 2, 1752, was a great day in the history of sleep.

That Wednesday evening, millions of British subjects in England and the colonies went peacefully to sleep and did not wake up until twelve days later. Behind this feat of narcoleptic prowess was not some revolutionary hypnotic technique or miraculous pharmaceutical discovered in the West Indies. It was, rather, the British Calendar Act of 1751, which declared the day after Wednesday the second to be Thursday the fourteenth."

Read more: The Gregorian Calendar—History http://www.infoplease.com/spot/gregorian1.html#ixzz3XJxaVG9I