A vote by millions of Egyptians on a new constitution should have been an occasion for national celebration. But overreaching by Islamists, including the country's president, has made the referendum that begins Saturday a source of division.

Even if the document is approved, President Mohammed Morsi will need to reach out to Egyptians -- including Christians, secularists and women -- who feel they have been excluded from a revolution they helped create. Yes, Morsi was legitimately elected, but that doesn't relieve him of the responsibility to preside over an inclusive government.

Critics of the constitution are divided over whether to campaign aggressively for a "no" vote or urge a boycott of the referendum. That disarray makes it likely that a flawed constitution will be approved by a misleadingly lopsided majority.

But Morsi should temper any exultation at such a result with the realization that a prosperous and internationally respected Egypt will have to be not only democratic but tolerant and law-abiding. Anything less will be a betrayal of the broad-based revolution celebrated in the constitution.