Being the religious holiday that it is, the extended Idul Fitri celebration has not left many people with a hangover. But still, we have a sour aftertaste from the open polemic that has developed between Muhammadiyah chairman Din Syamsuddin and Religious Affairs Minister Maftuh Basyuni.

Their disagreement is over when exactly Idul Fitri, the holiday that follows the end of the Ramadhan fasting month, fell this year.

For the last two years, Muhammadiyah under Din's leadership has broken a long-held tradition of celebrating Idul Fitri on a date jointly decided by a state-sponsored council of representatives of all the country's major Islamic organizations.

Last week, Muhammadiyah marked Idul Fitri on Friday, a day earlier than the date decided on by the joint council.

Basyuni, who presided over the meeting of the joint council, went over Din's head and appealed to all Muslims, including followers of Muhammadiyah, telling them they should celebrate Idul Fitri on Saturday.

This left Indonesia's second largest Islamic organization in a predicament. Some supporters followed Din, but quite a large number heeded Basyuni. Some mosques that had traditionally been Muhammadiyah's domain, in particular the Al Azhar Grand Mosque in South Jakarta, shut their gates Friday to the disappointment of many people who had gone there for Idul Fitri prayers.

Din criticized the minister for causing confusion among his followers. He said the state should stay out of the business of fixing religious dates, a task he said was better left to Islamic organizations.

Idul Fitri in Indonesia has always been celebrated on different days, attesting to the plurality of Islam in the country. This year, an Islamic sect in South Sulawesi marked it on Thursday, and yet another in Jombang, East Java, held prayers on Sunday. Such is the diversity of Islam in the country.

For the government, it seemed particularly upsetting that Muhammadiyah, which in the past had been accommodating, broke ranks for the second year in a row. While Idul Fitri celebrations went peacefully this weekend, many Muslims were left perplexed that Muhammadiyah decided to go it alone for the second year running. They rightly ask, what went wrong these last two years?

A closer inspection tells us that this is a return of the old rivalry between Nahdlatul Ulama (NU) and Muhammadiyah, the largest and second largest Islamic organizations in the country.

Basyuni, as was his predecessor, is not seen as an honest broker when leading the joint council meetings; Muhammadiyah representatives feel all the decisions on religious dates have gone NU's way the past few years.

This is not all that surprising since for the last several years the ministry of religious affairs has been led by figures affiliated with the NU: Said Agil Husin Al Munawar under President Megawati Soekarnoputri from 2001-2004, and Basyuni under Susilo Bambang Yudhoyono since 2004.

When Ramadhan begins and ends depends on the movement of the moon, and this is something that astronomers interpret and debate. Since this is not a fundamental issue, there is room for accommodation to reach consensus. This had been the case in the past, but apparently not anymore in recent years.

Vice President Jusuf Kalla was not wrong in saying that Muslim leaders should approach this issue like a trader: it's a give and take process; you win one day, you lose the next, but don't expect to win all the time lest you alienate the other side.

Accommodation is the key word. Idul Fitri is a celebration of one's victory not over others, but rather over one's own desire to give in to worldly temptations. Sadly, our religious leaders, both Muhammadiyah and NU, have failed to show the essence of the Idul Fitri spirit in recent years.

While Muslims should be free to decide when to celebrate Idul Fitri according to their own belief, it would still be nice if the two largest Muslim organizations in the country could come together each year and decide on one day. They have been accommodating in the past, surely they can be so again in the future.

There is no way of knowing where this old rivalry between NU and Muhammadiyah, which has been revived by this recent polemic, will lead us. From past experience, when the two largest Islamic organizations are fighting each other, the biggest losers are Muslims themselves. And since these groups represent the bulk of Muslims in Indonesia, the nation too will suffer heavily from the discord.

To both Din and Basyuni: patch up and make up.