Boko Haram continues its march toward making Nigeria an Islamic state. A few weeks ago, as the world focused on the terror attacks in Paris, the group continued its murderous rampage across the northern part of the country. Last weekend it killed dozens in Maiduguri. These are just the latest atrocities from Boko Haram, which has kidnapped hundreds of schoolchildren, murdered thousands of innocent men, women and children and driven hundreds of thousands more from their homes.

Unfortunately, all indicators point to the likelihood that the worst is yet to come.

Last month, Open Doors released its 2015 World Watch List, an annual survey of the most dangerous and difficult places in the world to be a Christian. This year’s report uncovered some startling and worrisome trends. In every region of the world — Africa, Asia and even in the Americas — persecution of Christians is growing. There was not one country on the 2015 list that decreased its acts of violence and persecution from the previous year. The escalation of violence over the past year was so great that the threshold used to create the list had to be increased. With nearly twice the number of Christians persecuted over the previous year, it’s clear why Christians should be very concerned.

What may not be as clear is why everyone else should care.

As Christians are expelled, Islamist extremists are taking their place.

What all Americans must understand is this: Ending the persecution of Christians is not just morally right; it is in our national interest. When we promote and defend freedom of religious expression throughout the world we are making the world safer for oppressed peoples, we are promoting a value that keeps extremism of any kind in check.

As Christians are expelled, Islamist extremists are taking their place.

After 13 years of creating the World Watch List in its modern form, Open Doors has observed that the persecution of Christians is a lead harbinger for discord in the wider society. If history teaches us anything, it is to pay attention to the signs that warn of geopolitical upheaval; in particular, the restriction of religious minority groups.  When religious minorities are first marginalized within a society, then targeted for attacks without notice from the free societies around the world, a purge is the next logical step in the mind of extremists.

For example, more than a decade ago, Christians in Iraq worshipped in relative peace. Even under the brutal dictatorship of Saddam Hussein, they faced no greater threat to their freedom than the general population of Iraq. But now Iraq ranks third on the World Watch List as one of the most brutal places for expression of the Christian faith.

In 2003, Open Doors began to take notice of a sharp increase in acts of violence against Christians and their places of worship in Iraq. Open Doors’ warnings to beware extremist groups forming in the North fell on deaf ears, and violence grew year after year. The Iraqi government was unwilling or unable to act, and the wider free world did little to help.

Since then, Iraq has steadily climbed on the World Watch List, and the number of Christians there has dropped dramatically. In 2003, there were approximately 1 million professing Christians in Iraq living side-by-side with their Muslim neighbors in relative peace. Open Doors estimated that in 2014, before the ISIS attacks, there were only 300,000 Christians left in Iraq, many of whom were living as internally displaced persons in the northern part of the country. That’s a loss of more than two-thirds of the Iraqi Christian community.

Responsible lawmakers and those concerned with the security of all free people should be asking themselves what is filling the void left by the dramatic decline of the Christian community. The answer is obvious: As Christians are expelled, Islamist extremists are taking their place.

It is time for the international community to pay careful attention to what happened in Iraq, because this scenario seems to be playing itself out again in Nigeria. The Western world cannot afford to continue to drag its feet.

Boko Haram, an Islamic terrorist group, has been turning up the heat on Christians in northern Nigeria for several years. Last year, at least 2,484 Nigerian Christians were executed or killed for their faith, the highest total of any of the countries on the World Watch List.

In January, I warned that Boko Haram might be duplicating the tactics and strategies of the Islamic State. Little did I know that, at that very moment, Boko Haram was slaughtering many Christians, along with people of other faiths, in the village of Baga. According to some reports, as many as 2,000 people were killed in what many agencies are calling “Boko Haram’s deadliest act.” Now Boko Haram is expanding its attacks into neighboring countries. If the past is any indicator, it will try to take over all regions of Nigeria as well as Cameroon, Niger and Chad. Unfortunately, the Nigerian government and the rest of the world are doing little to stop the assault on religious liberty.

An immediate concern for the region is the Nigerian presidential election, slated to take place on Feb. 14. The next week could bring even more attacks as Boko Haram seeks to further destabilize the nation.

Iraq and Nigeria are but two examples of how the persecution of Christians indicates a society that is about to tip into chaos. The world would do well to pay attention before it’s too late.

David Curry is the President of Open Doors USA. For nearly 60 years, Open Doors has worked in the world's most oppressive countries, empowering Christians who are persecuted for their beliefs. Christians are the most persecuted religious group in the world. Each year, Open Doors releases its World Watch List, a ranking of the 50 countries where Christian persecution is worst.