Christians celebrate the birth of Christ on December 25th, but that is not the correct birthday. The more accurate date is April 17th, 6 BC. How could we be so far off?
Well, it goes back to the original calendar that was commissioned to be created to replace the Roman calendar. The creator of that calendar, Dionysius, made two mistakes: (1) he did not recognize that the Roman Emperor Augustus was originally Octavian, thus failing to account for five years that Octavian ruled after defeating Mark Antony at the Battle of Actius in 31 BC, and (2) losing one year by omitting the year between 1 BC and 1 AD. In effect, Christ was born six years before the time affixed for his birth.
How do we arrive at April 17th? Astronomers have taken the constellations and planets back in time to examine the skies. April 17th, 6 BC is the best match for the planets Venus, Saturn, and Jupiter aligning near or in the constellation Aries, which was a sign for Judea. This was a very unusual configuration of planets and stars, so it would have been considered an important sign. The timing was right too because the Bible mentions that the shepherds were keeping watch of their flocks of sheep by night. This would have been in the warmer months, rather than the winter.
Tracing the trek of the three wise men, probably out of Persia, the astrological signs brought them west to Judea. They probably were told about the prophecy of a king of the Jews being born in Bethlehem, so they turned south, now following the planet Jupiter which was located in front of the constellation Aries and hovering over Bethlehem. This would have been about December 19th, 6 BC, again matching the position of the stars and planets at that time. The Bible indicates that the star went before them and stood over Christ. The star was Jupiter and it was “before” Aries or Judea and at that time, it had stopped right over Bethlehem as the wise men viewed it from Jerusalem.
The old Roman calendar started on the day that the Roman consuls entered office, based on the consular year. This probably was March 15th in the beginning, but later became January 1st. The Julian calendar, which began in 45 BC utilized the January 1st date. The months were designated January to December from the Roman period to the present. The start of the year was changed several times, but it always came back to January 1st. However, since the birth of Christ was the beginning of the BC/AD period, Dionysius’s mistakes about when Christ was born have been carried forward for centuries. This error has not been corrected, nor is it likely to be changed.
But we should celebrate the birth of Christ on April 17th of each year.