The year 2015 was the worst year for Christians in modern history due to "unprecedented, spreading and intensifying" level of exclusion, discrimination and violence, according to the 2016 World Watch List released by Open Doors USA, a watchdog group that advocates for Christians.

In their latest report, the group said more than 7,100 Christians were killed last year for faith-related reasons, up from 3,000 from the previous year.

Much of the persecution faced by Christians occurs in predominantly Muslim nations where Islamist extremism is prevalent, said the report. These countries which occupy the second to 10th spots in the list are: Libya, Iran, Sudan, Somalia, Pakistan, Syria, Afghanistan, Eritrea and Iraq.

The list, now in its 25th year, also showed that North Korea for the 14th consecutive time is still the top country that is most hostile toward Christians. "This is due to the country's communist state which views Christianity or religion as an aspect of Western culture,'' according to Gospel Herald.

Aside from the Islamic State (ISIS), Open Doors said other terrorist groups like al-Shabaab and Boko Haram have been identified as the leading culprits behind the abuse, torture, exploitation and killings of Christians, according to the Religion News Service.

The report also highlighted that ISIS and other extremist groups are "spreading'' not just in the Middle East but around the world.

David Curry, the president of Open Doors, said he hoped the list would bring attention to the plight of Christians across the globe as they face a "total lack of religious freedom, forced migration and even genocide.''

Citing the organisation's report, he said an average of 322 Christians are killed each month in different places for practicing or upholding their faith while 214 religious structures, including churches, are destroyed. Aside from these, 722 cases of violence against Christians are reported each month.

He suggested that identifying regions with a high number of cases of Christian persecution is vital in determining the stability of nations. "The persecution of Christians is a lead indicator of when countries are beginning to tip into chaos."

The organisation said the factors that contribute to persecution include authoritarian control by the government such as in the case of North Korea, hostility towards minority or non-traditional groups as well as lack of basic human rights.

Open Door's report is independently audited by International Institute of Religious Freedom.

The organisation works with Christians worldwide to "equip and encourage " those living under persecution while also helping churches in America advocate for the persecuted around the world.