CAIRO - Two days before a constitutional referendum it considered boycotting, Egypt's secular opposition finally launched its "no" campaign Thursday with newspaper and TV ads detailing the argument against the charter drafted by Islamist supporters of President Mohammed Morsi.

The Morsi camp has a simpler message: A "yes" to the constitution is a yes to Islam.

The deadly violence and harsh divisions of recent weeks - combined with the inability of most Egyptians to even comprehend the densely written 63-page document - have turned the vote into a stark choice on whether the largest Arab nation takes a serious step toward theocratic rule.

"This constitution is supposed to protect the rights of the minorities, but it is written by the majority for the majority," said Haitham Sherdi, a young opposition supporter from Cairo.

"If it passes, it will be used to crush the minority until they vanish," he added, referring to Egypt's Christian community.

Morsi's Muslim Brotherhood and other Islamists have been plastering posters across much of the country urging Egyptians to vote "yes to protecting [Islamic] Sharia [laws]."

The opposition's campaign on TV, in newspapers, and in fliers is focused on the slogan "A constitution to divide Egypt."

The opposition campaign began a day after the National Salvation Front - an umbrella group of opposition parties - announced it was calling on supporters to vote "no" rather than boycott the referendum. The delay reflected divisions within the alliance.

Reform leader and Nobel Peace Prize laureate Mohamed ElBaradei, who was among those initially favoring a boycott, made an emotional appeal to Morsi on Thursday to postpone the vote, warning of "the specter of civil war." He called on his supporters to vote "no" if the referendum goes ahead as scheduled.

Jehad el-Haddad, a spokesman for the Brotherhood's Freedom and Justice party, said that it would accept the referendum result regardless of the outcome.