The World Council of Churches general secretary Rev. Olav Fykse Tveit has condemned the twin attacks on Coptic Christians in the Helwan area south of Cairo in which 12 people were killed.
Ten people died when gunmen tried to storm the Mar Mina church, a Coptic Christian church near the capital Cairo in Egypt on Dec. 29, but were intercepted by police.
About an hour later, a Coptic-owned shop in the same area was attacked, leaving two dead.
"Once again, people going about their daily lives, in celebration of holidays, have suffered violent attacks," said Tveit.
"We must join together, not just to condemn these actions but to strengthen our pursuit of just peace, and our resolve not to allow extremist violence to separate us from each other."
The WCC issued an appeal to Egyptian President Abdel Fattah al-Sisi, to religious leaders and to governments across the region "to act swiftly and boldly to safeguard the fundamental religious rights of all faiths, to ensure security in the face of violence and to guarantee justice for all people."
Tveit assured those in Egypt and across the world that the WCC fellowship stands with them in prayer, mourning and steadfast hope.
"We pray for the victims and their families, and for the church leaders," he said, "and we seek God's mercy, love and grace that we may be empowered with strength to continue our pilgrimage of justice and peace."
"Through prayer, action and unity, we can bring a powerful force of love in the wake of terror and violence," he said.
Egyptian Coptic Orthodox Christians are frequently targeted in Egypt. During a Palm Sunday service in April at least 45 people were killed and scores more injured during bomb attacks in two separate cities.
In May nearly 30 people were killed when gunmen attacked a bus carrying Coptic Christians heading to a monastery and a Coptic Orthodox priest was stabbed to death in Cairo in October.
Egypt is a Muslim-majority country and its Christian minority - mostly members of the Coptic Orthodox Church - make up around 10 percent of the population.
The attacks have been blamed on, and in many cases claimed by, Islamists affiliated with IS the terrorist group that claims to act in the name of Islam.