THE month of Ramadan can be arduous for fasting Muslims, and Eid al-Fitr, the celebration of the month’s culmination, is eagerly anticipated. To mark a return to prandial normality, Muslims will feast and revel with family. But if previous years are anything to go by they will not be united in celebration. Muslims will celebrate on different days (June 15th is most popular this year), with divisions arising not only between countries, but within communities and even families. There are even anecdotal stories of calendrical fistfights breaking out in mosques. It seems bizarre that the simple determination of a religious festival is marred by such intense controversy. Why can Muslims not agree on the date?

The issue is linked to Islam’s lack of a central religious authority. In Muslim countries, the date of Eid is decided by a government, court or related body; in non-Muslim countries the decision is taken by individual mosques. Islam uses the lunar calendar, and the start of each month coincides with the birth of a new moon. Determining this occurrence is not straightforward. One area of contention is whether to take a traditionalist or modernist interpretation of Islam’s religious texts. Many scholars believe the month does not begin when the new moon is born, but when its crescent can be seen by the naked eye. On the night when the moon is expected to be visible, meteorological committees and ordinary people alike will turn questing looks to the skies. But this reliance on concrete sightings means that something as simple as a cloudy night can delay Eid by a day. Other groups, motivated by a less literal reading of the Koran, argue that Muslims ought to make use of modern science. The Fiqh Council of North America and the European Council for Fatwa and Research, two associations of Muslim clerics, say astronomical calculation is an acceptable methodology, which means that dates are known years in advance. They have led attempts to create a universal Islamic calendar, but to little avail.

Even among those who require sightings of the moon there is further disagreement. Some demand local sightings, but others feel an allegiance to Saudi Arabia, both spiritually and, thanks to the country’s massive funding programme for mosques and madrasas, financially. Many mosques will therefore align their calendars with those of Mecca. But racial separation within the Islamic community means mosques with congregations made up largely of immigrants from the Indian subcontinent will often follow the decisions of Pakistani or Indian authorities instead. This ensures that multinational families are synchronised, but by fragmenting Muslim communities in towns with multiple mosques, it can reinforce national tribalism.

The moon-sighting debate reflects wider divides in Islam. Different ideologies jostle for control, with Western modernists pushing for change against Saudi Arabia’s staunch traditionalism. Younger Muslims may be taking matters into their own hands: Google searches for “moon sighting” spike before each Eid. But as long as Islam remains decentralised and the Koran ambiguous, it is unlikely that Muslims will ever agree.