Some people might think that members of the jihadist group Islamic State (ISIS) do not fear anything or anyone because of the many barbaric atrocities they have already committed.

Fighters countering the vile terrorist organisation in northern Syria, however, recently discovered one of the ISIS militants' greatest fears: Getting killed by a woman.

According to an article in the Daily Express, the ISIS militants are afraid of their lives ending in the hands of female fighters because based on their beliefs, "they won't go to heaven" if this happens.

Because of this fear, more and more brave Christian women are now joining an all-female militia group in Syria fighting ISIS.

This small battalion of around 50 women, known as "The Female Protection Forces of the Land Between Two Rivers," is proving to be a potent force in driving the ISIS back in northern Syria.

These female fighters, mostly in their early twenties, get their combat skills by training in a camp in the north-eastern town of Al-Qahtaniyeh in Syria.

A report from The Independent said one of the battalion's new recruits is a 36-year-old hairdresser named Babylonia, who left her husband and two children to "protect their future."

Babylonia shared that it was her own husband who encouraged her to shatter the gender stereotypes and take up arms against the ISIS.

To the ISIS, women are only supposed to live "sedentary" lives as homemakers, wives and mothers.

According to an ISIS manifesto released in Arabic by one of the ISIS propaganda wings, women are "divinely appointed" to lead a life of responsibilities at home.

Telhelden, a 21-year-old commander of the all-female battalion, meanwhile told CNN that ISIS members are indeed "afraid of girls."

"They think they're fighting in the name of Islam. They believe if someone from Daesh [ISIS] is killed by a girl, a Kurdish girl, they won't go to heaven. They're afraid of girls," she said.