As the Islamic State, insurgents, and government forces battle in Syria, the population of Christians there continues to decline, from 1,250,000 in 2011 to less than 500,000 this year, down by 60%, according to ADF International, which advocates for religious freedom worldwide, CNS News reports.

In a sub-report submitted with the report Genocide Against Christians in the Middle East to Secretary of State John Kerry in March, the ADF International details the ongoing genocide of Christians and other religious minorities in the Middle East.

It notes that “Christians are the most persecuted religious group in the world” and that in at least 104 countries Christians are harassed and persecuted by governments and organizations.

The harassment includes “physical assaults, arrests and detentions, the desecration of holy sites and discrimination against religious groups in employment, education or housing,” reads the report.

Harassment of Christians “was the highest in the Middle East and North Africa (90% of countries),” reported ADF International. In Syria and Iraq, the persecution of Christians is carried out largely by radical Muslims, such as the Islamic State and Jabhat al-Nusra, said the ADF, according to CNS News.

In 2015, Syria’s population was approximately 20 million, said ADF International, and “92.8% of the population was Muslim, 5.2% Christian and 2% other.”

“The population of Christians dropped from 1.25 million in 2011 to as few as 500,000 today,” said ADF International in its report. “It is estimated that in 2015 alone, over 700,000 Christians in Syria sought refuge” in other countries.