Believers are often singled out, tortured and faced with the brutal choice of converting to Islam or being slaughtered, according to Christian Freedom International.
Those who refuse to comply have reportedly had their limbs cut off or have been crucified.
Research by CFI found that more than 200 million followers are facing persecution in 105 countries making Christianity the most at-risk faith group in the world.
More Christians have been martyred in the 20th and 21st centuries than during the previous 19 combined, the organisation has claimed.
The human rights group's president Jim Jacobson said: “Islamic State Militants in Iraq are using Christian churches as torture chambers where they force Christians to either convert to Islam or die.
“Islamic State militants are also stripping the former places of Christian worship of ancient relics which in turn are smuggled to Western collectors to help fund their terrorist activities." » | Scott Campbell | Sunday, September 20, 2015
