Standing before his class on Islam and Society at Al Rawda College, Sheikh Sad Sharaf cites the Koran to land a not-so-subtle jab at Hamas's recent takeover of the Gaza Strip.
When Muhammad died, explains Sheikh Sharaf, who is a member of the rival Fatah Party, burial was delayed until a successor could be agreed upon in order to avoid a power struggle over the Islamic caliphate. "This proves that infighting is illegal in Islamic terms," he concludes.
As Fatah struggles to contain the spread of Hamas in the West Bank, Palestinians like Sharaf are pushing for an Islamic critique to compete with the militant brand of religion practiced by the new rulers of Gaza.
Some advocate a liberal brand of Islamic politics that would support territorial compromise, while those with a strict interpretation of the Koran are attacking Hamas for straying too far by mixing religion and politics. But most agree that any challenge to Hamas must include a new spiritual formula.
The recent dominance of Islamic politics in Palestinian life is part of a pan-Arab trend in which religious parties have become the main opposition to regimes perceived as corrupt and undemocratic, says Hanna Siniora, codirector of the Israel-Palestine Center for Research and Information in Jerusalem.
"Thirty or 40 years ago, it was fashionable to be leftist and socialist. Now it is becoming fashionable in the Arab world to be an Islamist," he said.
Hamas's rise has coincided with growing disillusionment with the secular ideologies that dominated the Palestinian national movement starting in the 1950s.
Whoever comes out against Hamas will have to make up for lost time. For more than two decades, Hamas, originally a local branch of Egypt's Islamist Muslim Brotherhood, has entrenched itself in the fabric of Palestinian life through bold attacks on Israeli civilians and a broad web of charity institutions that filled a social and religious void left by a corrupt secular establishment.
Sharaf is trying to convince Fatah to establish a council of religious scholars that will be able to counter the rhetoric coming from Hamas.
He criticizes Hamas's advocacy of violence against Israeli civilians as well as its violent takeover of Gaza last month, which most Palestinians opposed.
"The Prophet Muhammad says, 'Don't kill those who don't use weapons against you. Don't kill a woman. Don't kill a baby,' " says Sharaf, who says he's a Sufi Muslim, a branch of Islam known for its theological mysticism and moderation.
A preacher in one of Nablus's central mosques and the host of an Islamic radio and television program, Sharaf says a growing number of Palestinians have sought him out for advice since the Hamas takeover of Gaza.
Although Sharaf says he believes in the religious idea of the creation of one Islamic kingdom as laid out in the Koran, the modern experience with states dominated by Islamic dogmatists have been negative, he says.
"Look at Sudan, Somalia, and the Taliban," he says. "Palestine should not be isolated from the international situation. The Islamic rule needs a long time before it can be effective."
The Sheikh complains that Fatah politicians have so far ignored his advice to enlist religious scholars for help. Palestinians inside and outside Fatah say installing a religious council within the party is the wrong strategy.
"Of course it is important to underline [that] the practices of Hamas are not consistent [with] what we believe are religious values," says Jamal Nazzal, a Fatah spokesman in the West Bank.
"But we cannot criticize Hamas from a religious point of view. We criticize Hamas from a democratic, secular point of view," Mr. Nazzal says.
The influence of religion in public life is becoming ubiquitous in the Palestinian territories, whether it's the head scarves worn by many women or the posters celebrating those killed as martyrs in the second Intifada which began in 2000.
Recognizing the Palestinian society's traditionalist leanings, Mohammed Dajani, a political science professor at Al Quds University, argues that the only way to challenge Hamas is by setting up a separate religious party that will push interpretations of Islam that back non-violence and tolerance.
Mr. Dajani named his party Wasatia – a term used in the Koran that means moderation. His party is reaching out to schoolteachers and Muslim clerics in a bid to counter Hamas.
"What we want to do is change the culture of the people," he says. "Our goal is to teach youth that suicide bombing is not Islam."
To be sure, Hamas's Islamist critics also include figures from more fundamentalist sects of the Muslim world. Palestinian Salafis assail Hamas's Sheikh Mouad Sawalhe, who is part of the Palestinian Salafi community, a group of Islamist fundamentalists who believe the political involvement of Hamas violates what they understand as a Koranic ban on Muslim political parties.
"Religion should be for worship and not for political goals," says Sheikh Sawalhe, sitting in the office of a Nablus cemetery where he helps prepare the dead before burial. "Does the pope interfere in the foreign policy of Rome?"
Funded by Saudi Arabian donors, Salafi leaders claim their community numbers 5,000 and is growing. They also plan to open a religious academy in Nablus.
In the Salafi view, a secularist like Abbas who sins because he doesn't observe Islamic dictates is preferable to a group like Hamas which sins in the name of Islam. At the same time, Salafis believe the place of believers should be unconditional support for the regime.
"But what about the situation where there are two prime ministers, one in Gaza and one in the West Bank," asks one student back in the college class on Islam and government, referring to the Palestinians current dilemma.
It is a question that Sharaf prefers to avoid. "The truth is that we are living in an exception," the lecturer says. "Let's return to the caliphate."