Muslim Brotherhood heavyweight Essam El-Erian has cited the killing of Christians as one of three major reasons for the demise of the Mubarak regime in 2011.
In comments posted on Facebook, El-Erian, vice-chairman of the Brotherhood’s Freedom and Justice Party (FJP), described the bomb attack on the Two Saints Church in Alexandria, which killed 23 people on 31 December 2010, as a "disaster."
The "scandalous" rigging in the 2010 parliamentary election by Hosni Mubarak's National Democratic Party, which led the FJP and the liberal Wafd Party to withdraw from the second round, was another major mistake by the Mubarak regime, he said.
Mubarak's third key error was grooming his son to replace him as president despite opposition from the powerful armed forces.
El-Erian's comments come after Coptic Orthodox Pope Tawadros II criticised President Morsi for failing to protect Christians in Egypt following two recent outbreaks of sectarian violence.
Deadly clashes erupted in Al-Khosous in Qalioubiya on Saturday after a group of Christian teenagers allegedly daubed what some Muslims deemed offensive symbols on the walls of an Al-Azhar institute in the town.
Four Christians and one Muslim died in the violence that followed.
On Sunday, a funeral for the Christian victims of the violence was held at St Mark's Coptic Orthodox Cathedral in Cairo. As mourners were leaving the cathedral they were attacked by unknown assailants. Two people died and at least 90 were injured in the ensuing violence.
Police fired teargas and birdshot directly into the cathedral compound, sparking uproar among the Christian community.
The pope said President Morsi had failed to protect the cathedral as he had previously promised.
There was a dereliction of duty and the responsibility lies with the security apparatus, the pope said.