The draft constitution, finalized by Islamists on a Constituent Assembly despite a boycott by liberals and Christians, has polarized Egypt, bringing out huge rival street rallies by both camps in the past four weeks. Opponents of Morsi accuse him of ramming the document through and, more broadly, of imposing a Brotherhood domination of power. Morsi supporters, in turn, accuse his opponents of seeking to thwart a right to bring Islamic law they say they earned with election victories the past year.
Egypt's main Coptic Orthodox Church and smaller ones have taken an uncharacteristically assertive approach in the constitutional struggle. They withdrew their six members from the Constituent Assembly to protest Islamist domination of the process and later refused to send representatives to a "national dialogue" called for by Morsi.
The new Coptic pope, Tawadros II, enthroned last month, publicly called some of the charter's articles "disastrous."
In response, the Muslim Brotherhood — which usually keeps a moderate tone toward Christians — has turned toward more inflammatory rhetoric.
Senior Brotherhood figure Mohammed el-Beltagi in a newspaper interview this week depicted mass anti-Morsi rallies outside the presidential palace in Cairo this month as mainly made up of Christians, hinting at a Christian conspiracy against the president.
In a recent speech, Safwat Hegazi, a famous Islamist preacher linked to the Brotherhood, warned Christians against joining forces with former Mubarak regime figures to topple Morsi.
"I tell the church, yes, you are our brothers in Egypt, but there are red lines. Our red line is Morsi's legitimacy. Whoever dares splash it with water, we will splash him with blood," he said, using an Arabic saying.
In Assiut, Tobia, Ramzy and other Christian activists spoke of an atmosphere of intimidation ahead of the vote, including the large Islamist march.
They said threatening messages were sent on mobile phones and on social networking sites. During an opposition demonstration on Dec. 7 outside the offices of the Brotherhood's political party in Assiut, suspected Morsi supporters seized six protesters — five Muslims and one Christian — beating them and shaving the head of one.
With tension building up over the last four weeks, many Christian voters registered at polling centers located in predominantly Muslim areas did not vote, fearing violence, they said.
Those who made it to polling centers in districts with significant Christian populations were soon frustrated by the long lines or delays, which activists said was intentional. In some cases, they said, Islamists who had voted elsewhere then went to stand in lines in mainly Christian areas to make them longer, increase delays and prompt Christians to give up and leave.
Two Christian clerics said that outside the province's main cities, only about 12 percent of registered Christian voters left their homes on Saturday to vote and that no more than seven percent were able to cast their ballots. They based the figures on statistics gathered by members of the Coptic Church's youth group who monitored voting across the province. The two clerics spoke on condition of anonymity because of sensitivities over the church role in political issues.
In the Christian village of el-Aziyah, only 2,350 of the village's 12,100 registered voters cast ballots on Saturday, according to acting mayor Montaser Malek Yacoub.
Yacoub is among the growing number of Christians who are pushing back against persecution.
He has taken advantage of the tenuous security situation of the past two years and built two churches without permits and reclaimed a large area of state-owned desert that lies outside the village's boundaries toward a rock mountain. Under Mubarak's rule, Christians rarely received permits to build or renovate churches.
"Let me just tell you this: As far as I am concerned, this is our country and everyone else are guests," he said. But "we're ready to cooperate with anyone who shares Egypt with us."