As Arab leaders sip tea and discuss what to do about Syria in the heavily guarded (yet still vulnerable) compounds of Baghdad, one thing is clear: No one cares about Arab nationalism anymore.The leaders of Saudi Arabia, the United Arab Emirates, Qatar, Bahrain and Oman refused to attend the summit. The predominately Sunni Arab countries in the Gulf are not comfortable with how cozy the Shia-led government in Baghdad is with Iran these days. Iraq’s new leaders wanted to use the summit to show how stable Iraq had become, to reassert Iraq’s position as a leader in the Arab and Gulf worlds, and to proclaim it, at long last, open for business. Instead, it seemed to signal the death of Arab nationalism and cement, for now at least, the Sunni-Shia divide within the Muslim world.Arab nationalism is now largely a vanished cause. Once it aspired to unite Sunni, Shi’a, and Christian Arabs under a secular banner. It is the official ideology of the Ba’ath party in Syria and the outlawed Ba’ath Party in Iraq, and it was once touted by Nasser as well. But now it is pretty much dead. Sectarian differences between Arabs are seen as more important than common language and culture. Nouri al-Maliki, the Iraqi Prime Minister, ignoring the snubs from the Gulf Arab countries, tried and failed to proclaim the triumph of the new camaraderie in the Arab world: “The summit results, in which Iraq and Arab countries have resumed relations, represents a new turning point in the relations among Arab countries,” he said. Take a look around, Mr. Maliki.One day the pendulum might swing back. In some future world, Egyptian, Saudi, and Iraqi Arabs might cross the sectarian divide as they once did, seeking common bonds instead of emphasizing, often violently, their many differences. But that day is not today. Iraq may be finally emerging from the shadow of Saddam’s isolation, but for now Arab nationalism is dead.