In a video released on Sunday, 21 Egyptian Coptic Christians were beheaded by Libyan extremist group, which swear allegiance to the Islamic State Iraq and Syria (ISIS). Christian leaders around the world, including Pope Francis, Franklin Graham, condemned the brutal murders of the fellow brothers in Christ.  

"The blood of our Christian brothers is a witness that cries out," said Pope Francis, according to Vatican Radio Report, on Monday. "If they are Catholic, Orthodox, Copts, Lutherans, it is not important: They are Christians. The blood is the same: It is the blood which confesses Christ."

Francis said the hostages, believed to be laborers from Egypt working in Libya, are now "martyrs."

In the five-minute video titled: "A Message Signed With Blood to the Nation of the Cross," the executioner speaks in English and points his knife toward the Mediterranean. "We will conquer Rome, by Allah's permission," he says, according to CNN.

The statement in the video were unlike those of other Islamist groups in the region, for it did not mention the Egyptian state, or other powers in Libya's civil war, in which both of the country's rival governments claim to be combating ISIS in Libya.

Instead, the group's ultimatum is directed towards "Rome," and Christians, who are labelled "The people of the cross, the followers of the hostile Egyptian Church," CNN reports.  In the Bible, Apostle Paul, who wrote half of the New Testament, has aimed at bringing the Gospel of Jesus Christ to Rome, which was the center of the world then. In an apparent challenge, the Islamic  The phrase could also mean the west where Christianity is the dominate religion.

The video ends with the Mediterranean waves dyed red from the blood of the murdered men.

Before the video was released, Twitter accounts linked to the Libyan branch of ISIS had revealed on Friday the photos captioned, "The Islamic State carrying out the execution of the Coptic prisoners in the province of Tripoli."

In the photo caption, the extremist claimed the execution was for the "revenge for the Muslim women persecuted by Coptic crusaders in Egypt."

The latest executions of the Egyptian Christian workers, who were captured in Sirte, on Libya's coast, in December and January, stirred horror in the small Egyptian village of El Aor, home of many of the abductees. "It was a dark day in the village. Everyone was crying," said Mina Thabet, a representative of Egyptian Commission for Rights and Freedoms.

"The video released today once again demonstrates the incredible evil that is being perpetrated by militants loyal to the Islamic State. We mourn alongside of the families of those who have been killed, along with all Egyptians who saw their countrymen brutally killed, and with Christians around the world," said Todd Daniels, International Christian Concern (ICC) regional manager for the Middle East.

"These Islamic extremists continue to claim their inspiration for their actions from their religious beliefs and have once again committed horrific violence in establishing their religious beliefs. We strongly urge the Egyptian government to act swiftly to provide protection for its citizens who remain in Libya and face continued threats if they attempt to flee the country."

Since the dismantling of the Gaddafi regime in 2011, Libya has been in a state of disarray. The region faced a civil war, splintering Libya between an internationally recognized government in the east and Islamists who control Tripoli in the west. The instability has allowed ISIS to expand its influence into pockets of North Africa.

Billy Graham's Son Franklin Graham, CEO of BGEA and Samaritan's Purse, warned of the continuous threat that ISIS poses to the global Christian communities.

"Can you imagine the outcry if 21 Muslims had been beheaded by Christians? Where is the universal condemnation by Muslim leaders around the world?" he said. "As we mourn with the families of those 21 martyrs, we'd better take this warning seriously as these acts of terror will only spread throughout Europe and the United States."

Rap artist Lecrae wrote on Facebook: "Prayers go out toward my Egyptian brothers and sisters who lost fathers, brothers, and sons, and friends. May Gods comfort and Justice prevail."

Christian singer and artist Jeremy Camp expressed his sorrow, "With a deeply heavy and broken heart I am praying for my brothers and sisters and the persecuted church. Jesus come soon!"

Christian author Karen Kingsbury wrote, "Grieving the loss of my brothers in Christ. Grateful for their sacrifice and example. This is Christianity. #willingtodieforJesus."

In early January, ICC has started a petition to urge the government in the "strongest possible terms to increase protections for the expatriate Coptic community in Libya." Egyptian Christians with relatives in Sirte and other parts of Libya say many of their family members are trapped, with no way to travel without risking further abductions.

After authenticating the video, Egyptian President Abdel Fatah al-Sisi launched air strikes against targets in Libya hours after vowing to avenge the deaths.