Harold Camping, the 89-year-old former civil engineer, has failed at least two times in his prediction of doomsday. Harold Camping states in his book 1994? that the end of the world may occur somewhere between September 5th and the 27th of 1994, and he does not know the exact day because scripture says "no man knows the day nor the hour" (Matt.24:36) but according to Camping we can certainly know the month and the year that Christ will return. After September came and went, he proclaimed December 25, 1994 as the end of the world.
Please note, here it comes one of the contradiction, that in 1992, Camping contended that he can certainly know the month and the year, but not the date. Meanwhile, Camping based his calculations on numbers and dates found in the Bible and, at the time, said that he was "99.9% certain" that his math was correct. But the world did not end in 1994. Nor did it end on March 31, 1995 — another date Camping provided when September 1994 passed without incident.
Again, this time around, his predictions are based on taking direct quotes and stories from the Bible and applying them to numerological formulas. May 21, 2011 is exactly 7,000 years since the flood in the biblical story of Noah's Ark.
Why, this time, Camping is so sure that, the exact date of May 21 2011 will be the doomsday?
Another inconsistency is that according to Camping the seventy sevens of Daniel 9 are literal years, except for the last three in a half. He calculates the years precisely to the death of Christ which he says occurred 33 AD. He then turns around and says the last three in a half years equal 2,000 years. Probably this is the main reason why he keeps miscalculating. Remember, the calendar used back then was a total different one from the one we are using now. In Camping's computations he does not take into account the different changes in calendarss. Before the Julian calendar was established in 45 BC Rome had a lunar calendar which was often shortened or lengthened to manipulate elections. Because the Julian calendar was 11 minutes and 14 seconds longer than the actual solar year Pope Gregory XIII decreed in 1582 that ten days be dropped from that year and that leap year be omitted very one hundred years except when the number of years was divisible by 400. The Gregorian calendar is what we use today. What did the Jews use to reckon time? Recently published fragments from the Dead Sea Scrolls in cave four indicate that the scribes of Qumran started reckoning time from the fourth day of creation. Their year consisted of 364 days with lunar months alternating between 29 and 30 with a full moon every third year on the first day of creation week(5). The Mishna has a different way of reckoning time. This makes it very difficult to pinpoint exact dates as Camping has done.