The Islamic State has caused a lot of damage, taken many lives, incited chaos and fear, and targeted non-Muslims. Because of this, Christians have taken up arms to fight against the terror group.

(REUTERS/Stringer) Iraqi Christians volunteers, who have joined Hashid Shaabi (Popular Mobilization), allied with Iraqi forces against the Islamic State

It was reported in July last year, that a group of about 1,000 Christians had banded together to form the Iraq Christian Resistance called Babylonian Brigade. They were training with the government-sanctioned paramility group, the Popular Mobilization Forces, comprised of Shia and Sunni militias.

"[ISIS] displaced us from our houses, they took our money, killed our young men and women and they took our properties," Rayan al-Kildani, the commander of the Babylon Brigade, told NBC News. "Therefore, Christians decided to fight the terrorists of ISIS. By the will of God we will avenge what happened to our community."

More recently, BBC correspondent Owen Bennett-Jones went to see the leader of the Babylon Brigade to find out more about the group.

Kildani refused to give the number of people they have now, saying that it's a military secret; however, another militia man had already disclosed this information to Bennett-Jones. The report says there are about 100,000 armed volunteers in 30 popular mobilization units that were formed in the past two years. The militias, as a whole, are reported to be receiving a total of about $1.4 billion per year from the government.

Kildani stated that their group has fought alongside Muslim militias, and that they are "the first Christian power in Iraqi history." He also claimed to having good defenses and "no-one is going to do anything bad to the Christians."

"We have to fight. We have to defend ourselves," he said, adding, "Jesus himself told us that if you don't have a sword you should go out and buy one."

Bennett-Jones admits to having been surprised at this, and Kildani's assistant showed him Luke 22:36, a verse that theologians have apparently debated over for a long time.

It goes, "If you have a purse, take it, and also a bag; and if you don't have a sword, sell your cloak and buy one."