Q: Why don't the celebrations of Passover and Easter fall consistently on the calendar each year?
A: Around the fourth century, the Christian church chose to celebrate Easter beginning the first Sunday following the Spring Equinox. Jewish believers continue to follow the Jewish calendar from year to year. Sometimes Passover and Easter are at approximately the same time and sometimes they differ by a week or two. Every now and then they are separated by a month.
Just as the Christian calendar adds one day to February every four years, the Jewish calendar, with its months based upon the lunar system, adds one whole month every so many years to conform the lunar calendar to the solar calendar.
Q: Please explain to me the difference in the Jewish and Gregorian calenders and why there is approximately 240 years difference between the two.
A: The Gregorian calendar was an attempt to begin the new date (A.D.) based upon the year that Jesus was born. In the end, the calculation was incorrect by a number of years due to missed historical facts. It is now known that Herod the Great died in the year 4 B.C. Since he was alive when Jesus was born, that already puts Christ's birth earlier than the year 4 B.C. and not A.D. 1. Furthermore, we also know from Matthew two that Jesus was two years old at the time the wisemen and Herod met. If we put these things together, we can determine that Jesus was born between 7 and 6 B.C., which is why the Gregorian calendar is off by that many years.
The present Jewish calendar is based upon a calendar put together by rabbis in the second century A.D. and they, too, did not have all of the history and details necessary to be accurate. When the rabbis put their calendar together, they tried to go back to the time of creation in Genesis one. This was done over 4,000 years after that event and, here again, a lot of information was lacking when the rabbis tried to put this together. Taking the chronologies of the Bible literally, and taking what we know from post-biblical history where chronology is fairly well established, we know the Jewish calendar is short by about 250 years.
It is recognized by scholars and historians that both calendars are not 100% accurate but it is too late to do anything about this now.
Q: Please explain the discrepancy between the Jewish (5756 presently) and Western (1995) calendars. Also, how did the term, “before the common era” (B.C.E.) originate?
A: To answer your question, the reason there is a difference between the Christian and Jewish calendars is because the Christian (or Gregorian) calendar tries to begin with the year of Christ's birth, though they missed it by about six years. Based upon that premise, it is probably six years later than our calendar indicates.
The Jewish calendar is based upon rabbinic calculations from Creation and, so, the rabbis believe that Creation occurred 5756 years ago. Just as the Christian calendar is off by about six years, the Jewish calendar is off by about 250 years. It is really about the year 6000 since Adam was created. That is the reason for the difference in years and neither calendar is 100% accurate.
The references of B.C. (before Christ) and A.D. (the year of our Lord) are based upon the Christian dating system. This creates a problem for Jewish people who prefer not to use references to Christ, so they opt for different designations for the same time periods: B.C.E. (i.e., B.C.) and C.E., “common era” (i.e., A.D.).