The Copts are the Middle East's largest religious minority, and have long suffered sectarian violence that culminated in attacks on churches by supporters of ousted Islamist president Mohamed Morsi last year.
The Islamists have been crushed following Morsi's overthrow by the army in July. Many of the Christians hope Sisi, the leading candidate in the May 26-27 election, will keep it that way.
"He is the country's saviour. During the (Muslim) Brotherhood's rule, Christians were persecuted," said Maged Sabri, as he attends a mass at a church in the working class neighbourhood of Shubra.
For decades, Egypt was ruled by strongmen from the military who often rounded up members of Morsi's Muslim Brotherhood.
Copts "are hoping that with Sisi they will see a reinstatement of a security system that ensures they become less vulnerable to assault," said Mariz Tadros, a fellow at the University of Sussex's Institute of Development Studies.
The Copts have complained of discrimination by the government and sectarian violence, but Morsi's Islamist rhetoric and his supporters' incitement during his year in power sent a chill through the minority.
"Without (Sisi) the Brotherhood would have taken control of the state," said Amir Bessaly, another worshipper at Cairo's Virgin Mary church.
The Coptic Pope Tawadros II has hailed Sisi for "saving" the country from Morsi, but has stopped short of explicitly backing his candidacy.
When Sisi announced in a televised address Morsi's overthrow on July 3, he was flanked by Tawadros II along with Muslim religious leaders and opposition figures.
The pope's appearance fuelled Islamist allegations that the Copts played a central role in ending Morsi's elected government, although millions of mostly Muslim Egyptians had taken to the streets demanding his resignation.
On August 14, when police killed hundreds of pro-Morsi protesters in Cairo, the Islamist's backers attacked churches across the country.
- Islamist attacks unite many -
The attacks by the Islamists, seen as enemies by the state and many Muslim Egyptians, have fuelled a new found sense of ecumenism in a country where sectarianism has run deep for decades.
Sisi himself was not always a hero for the Copts.
He was a member of the ruling military council following the ouster of former president Hosni Mubarak in 2011, when 26 Copts were killed in clashes with soldiers outside the headquarters of state television.
One protester's skull was crushed by a military armoured vehicle as it ran over Christians. Three soldiers were also killed in the clashes. "They attacked us. Christian sons of dogs," a soldier told state television at the time.
The Copts had been protesting over a church arson in southern Egypt, and after sporadic and deadly sectarian clashes in the months following Mubarak's overthrow.
For many Copts, those events have been overtaken by more violence under Morsi, such as when police attacked the papal headquarters in Cairo during clashes in 2013, and after his ouster.
Not all, however, wish to throw their lot in with a potential strongman hailing from the military, and many who do say they will continue to push for more rights and access to senior state position.
While the Coptic Church represents perhaps a majority of the Christians, youths and dissidents may cast their ballot for Sisi's only rival, left wing politician Hamdeen Sabbahi.
Under Mubarak, who ruled for three decades, the Church was often treated as the only institution allowed to speak for the community, a tradition likely to continue under any president.
"The new political power is looking to use the traditional religious authorities... because it wants popular support and those institutions can provide it," said Ishak Ibrahim, a researcher with the rights group the Egyptian Initiative for Personal Rights.