The Islamic extremist group Boko Haram has released a video showing the execution of two Christian aid workers and the group also vows to kill every Christian they capture in the future.

According to Morning Star News, the video was posted on Sept. 22 on the group's Amaq news agency website. It shows two young men, Lawrence Duna Dacighir and Godfrey Ali Shikagham, both members of the Church of Christ in Nations (COCIN) on their knees while three heavily armed men stand behind them. Both men are then shot.

Speaking in the Hausa language in the video, one terrorist then says they have vowed to kill every Christian they capture in revenge for Muslims killed in past religious conflicts in Nigeria.

Previous large-scale clashes between Muslims and Christians occurred in Jos in 2001 and 2008.

Dacighir and Shikagham had gone to Maiduguri to help build shelters for people displaced by Islamic extremist violence. The pair, originally from Plateau state's Mangu County, was captured by Boko Haram, now called the Islamic State in West Africa Province (ISWAP), as they carried out their work in displaced persons camps.

The two men's identities were confirmed by a family member, the Rev. John Pofi, a COCIN pastor.

"Lawrence and Godfrey left Abuja for Maiduguri in search of opportunities to utilize their skills for the betterment of humanity and paid with their lives," Pofi told Morning Star News. "We will never get their corpses to bury. The community will have to make do with a makeshift memorial to these young lives cut short so horrifically."

If the federal government had created economic opportunities for those tempted to join extremist groups and had returned security to the country, his cousins would not be dead now, Pofi said.

"We must ask ourselves if this is the kind of country we want where young men who are earning an honest living are brutally killed while those who abduct and kill others are invited to dialogue with government and paid handsomely," he said.

In a letter last week to the United Nations secretary-general, attorney Emmanuel Ogebe of the U.S.-Nigeria Law Group, a legal consulting firm with an emphasis on human rights, expressed concern that the Nigerian government did not condemn the killing of the two men even though they were helping to provide shelter for displaced Nigerians.

Ogebe wrote that workers for international aid group Action Against Hunger kidnapped in July issued a distressed plea for government help with no notable administration response. On Wednesday (Sept. 25), Action Against Hunger announced that one of its workers being held hostage had been executed.

"More executions of humanitarian workers could yet occur," Ogebe wrote to the U.N.

Nigeria ranks 12th on Open Doors' 2019 World Watch List of countries where Christians suffer the most persecution.

The current insurgency started in Nigeria in 2009. Since that time, Boko Haram has reportedly killed tens of thousands of people and has displaced 2.3 million from their homes. At one time, it was the world's deadliest terror group, according to the Global Terrorism Index.