ISIS has released yet another graphic video showing the mass execution of Christians in Libya, and has vowed to continue killing Christians until the world submits to Islam.

The grisly footage appeared at the end of a 30-minute video by the Islamic State terror group's Al Furkan media arm, showcasing its treatment of Christians under its control in Syria and Iraq.

Several Christians are interviewed in the film, and explained how they accepted "dhimmi" status upon themselves as an alternative to being killed by the jihadists. 

Under Islamic law (sharia) dhimmi status is granted to Jews and Christians ("the people of the book"), who opt not to convert to Islam or die. It allows them to practice their religion but with several restrictions designed to humiliate them into recognizing the "superiority" of Muslims, and in addition to paying a special tax to Muslim authorities known as "jizya." 

In the video, ISIS claims its jizya tax amounts to four grams of gold for the rich, two grams for "average" people and one gram for the poor.

But the worst segment of the video came at the end, when two separate groups of black Christians are shown being frogmarched by masked gunmen, in carefully choreographed scenes bearing a chilling similarity to the execution of dozens of Egyptian Coptic Christians in Libya last year.

Like the Coptic Christian victims, one group is marched along a beach in Libya; the other group is filmed in a desert somewhere inland.

The captured men - most likely migrant workers - are introduced as "Worshippers of the cross belonging to the hostile Ethiopian Church," before a masked terrorist speaking perfect English addresses the camera.

Repeatedly pointing his pistol at the camera, and speaking with what is possibly an Arab-American accent, he declares the impending spectacle will prove that "the Muslim blood that was shed under the hands of your religion is not cheap" - likely a reference to operations by Ethiopian forces against Al Shabaab Islamist terrorists in Somalia.

Speaking to the Christian world in general, he adds: "you won't have safety, even in your dreams, until you embrace Islam."

The video ends showing the kidnapped Christians executed in two groups, apparently in different parts of the country. While one line of captives is mowed down by gunfire, another group are seen screaming in pain and terror as the jihadists saw off their heads, their blood mixing with the sea waves.