Christianity has its controversies, like the original date on which Easter is based, but it's a celebration and therefore symbolic.  

Muslims are a little more rigorous in their approach and there has been turmoil over the possibility that quasi-scientific authorities in Arabia  misread the skies and mistook Saturn for the moon when it declared Ramadan and its daily fasting over last week.  If so, it caused people to starting feasting a day early.  You can imagine how the more militant Muslims feel about that. 

Sighting the new moon crescent has always been difficult and a special Hilal panel, or moon-sighting committee, receives testimonies from veteran Muslim moon gazers that in fact the lunar month is over. Religious authorities in Arabia declared Ramadan ended last Monday August 29 and the three-day Eid al-Fitr festivities could begin. 

Many nations follow the rulings from Arabia, but not this year; in Indonesia, there was such doubt that the astronomers and Muslim bodies extended the Ramadan fast for another day and didn’t celebrate the Eid until sundown Tuesday. 

Saudi and Egyptian astronomers, too, questioned the veracity of the moon sighting and issued a statement saying there was no way it could have been sighted last Monday because it had eclipsed before sunset. If they saw anything, it was the planet Saturn and not the moon, the astronomers said.

Did Muslims Miscall End of Ramadan Fast? Arieh O’Sullivan The Media Line

H/T The Science Pimp