Egypt is perilously close to seeing its revolution stolen by Islamists intent on replacing Hosni Mubarak's dictatorial rule with a theocracy. President Mohamed Morsy should reverse course and cancel Saturday's scheduled referendum on a deeply flawed constitution. The Obama administration needs to drive home that point with the threat of reducing U.S. aid. If approved, the constitution would be a major setback for women's rights, invite persecution of religious minorities and impose the views of the Muslim Brotherhood on all Egyptians.

It could also tear the country apart.

How tragic for all those who took to Tahrir Square to topple Mr. Mubarak with the dream of bringing true freedom and democracy to their nation, with authentic equality for men and women and respect for people of all faiths, or non-faith. Ironically, the Muslim Brotherhood and more radical groups, such as the Salafis, were forced to clandestinely organize to survive the long years of persecution by Mr. Mubarak's regime, which considered Islamic fundamentalism the government's greatest threat.

When the country moved too quickly to elections and creation of a constitution, the Brotherhood and supporting groups had a major organizational advantage that translated to a large electoral victory. They then used those numbers to make their constitutional power grab, with opposing groups abandoning the constitution-writing process when the Brotherhood's intent to ignore alternative views became clear.

The constitution is a farce. It cites Sharia, the moral code and religious law of Islam, as the main source of legislation and calls for consulting the scholars of al-Azhar, an ancient order of Muslim theology, on Sharia matters. The proposed constitution speaks of gender equality, but states the government must balance that with the need to protect the "true nature of the family" and a "woman's obligations to family," buzz words for keeping women in their subservient place.

Protestors, decrying the constitution and urging President Morsy to scrap it in favor of drafting a document that respects the rights of all, were greeted with counter-protestors shouting, "We sacrifice our soul and blood for Islam." In one instance Islamic fundamentalists attacked secular protestors, with several killed and hundreds injured in the clashes.

President Morsy can expect this to be just the start if he allows the constitution to be rammed through on Saturday. The president's recent order authorizing soldiers to, if necessary, arrest civilians to keep order at polling stations was chillingly reminiscent of the intimidatory elections of the Mubarak years.

The elation of Egypt's Arab Spring grows ever more distant.