The eradication of Christians has become a hallmark of Islamist extremism in the Middle East, Africa, and Asia. This is an egregious and deepening human-rights issue that the West has largely overlooked. The recent attack in Kenya is but the latest example. In the predawn hours of Holy Thursday, four black-clad al-Shabab militants burst onto the campus of Garissa University College, a pluralistic outpost in a Muslim pocket of the largely Christian country of Kenya. They shot their way through the security gates and began firing their AKs, shouting, "God is great." At first, they killed randomly with a spray of bullets. But the attack, which authorities assess was "coordinated" by a former teacher at a local madrassa, took on a particularly religious dimension as the hours wore on. The killers became methodical, selecting their victims from among the students on the basis of religion. They bypassed a mosque and a Muslim prayer gathering and made their way to an ecumenical Christian prayer group, lobbing grenades and shooting into the chapel space, slaughtering 22 of the 29 worshipers. Then, the gunmen - one the son of a Kenyan official and a promising law student - stormed through a women's dormitory of sleeping students and continued their rampage. Those who could prove they were Muslim by reciting the shahada, the Quranic verses that constitute the Islamic profession of faith, were freed. But "if you were a Christian, you were shot on the spot," Collins Wetangula, vice chairman of Garissa's student union, told the international media. Some had their throats slit. By nightfall, 148 students and staff lay dead. Though these facts were duly reported, many news outlets focused on al-Shabab's political goal of retaliation against Kenya's military. Downplayed was the obvious religious goal. Al-Shabab was on a strategic mission to target Christians at Easter time. That is, while the terrorists indiscriminately killed both Muslims and Christians, it was only the Christian students they sought out and deliberately murdered. The same pattern occurred when al-Shabab attacked Nairobi's Westgate Mall in 2013. The media have ignored the merciless religious cleansing campaign al-Shabab has waged in Somalia. The victims have included native Somalians, such as the children of converts to Christianity, whom they beheaded, and foreigners, such as an Italian Catholic nun, Sister Leonella Sgorbati, Somalia's Mother Teresa, whom they shot in the back outside the hospital where she had nursed the poor for more than 40 years. Inexplicably, neither President Obama nor Secretary of State John Kerry bothered to mention the Christians in their condemnations of the Kenya attack, as if al-Shabab's religious motives were irrelevant. In official American parlance, targeted Christians were simply "lives lost," "Kenyan people," or "innocent victims." Contrast those remarks with the administration's condemnation of the lethal attacks by the Islamic State last weekend against civilians in Syria. That statement specifically cited the victims' identities - "Ismailis and Alawites" - both Muslim sects considered heretical by the Islamic State. Or the administration's past statement that "strongly condemn[ed] the dangerous and provocative attacks on a mosque" in Israel. How can this double standard in identifying victims be explained? Meanwhile, Christians are being persecuted for their religion in numbers exceeding those martyred during the Roman Empire. Some examples: April 14 marks one year since the kidnapping and disappearance of 219 Nigerian schoolgirls by Boko Haram. The overwhelming majority of these girls were Christian, though this is rarely acknowledged in the media. Boko Haram has deliberately destroyed hundreds of churches in northern Nigeria and forces Christian men to convert at gunpoint. On March 15, in Punjab, Pakistan, the Taliban blew up a Catholic and a Protestant church, both filled with Sunday worshipers, killing 14. In early March, in Syria, 33 Khabour River villages of Assyrian Christians were attacked by Islamic State. The 5,000 defenseless residents were driven into exile, abducted, or killed. On Feb. 15, 21 Coptic Christians, who had been singled out from their migrant housing, were beheaded on a Libyan beach by an Islamic State affiliate. (In its condolence statement, the Obama administration referred to them only as "Egyptian citizens.") In Iraq over the summer, Islamic State imposed its convert-or-die policy on the 2,000-year-old Christian community of Ninevah. Christians were deported or killed, and their homes marked with an "N" for "Nazarene." More than 100,000 of them now survive on international aid in Kurdistan. Their ancient churches and monasteries are being systematically blown up or desecrated. This terror occurs in the context of war and power struggles from which Muslims also suffer. But simultaneously, a war of religious cleansing against Christians and other vulnerable minorities is evident. After the Garissa massacre, Pope Francis condemned the world's "complicit silence" regarding the persecution of Christians. "I hope that the international community doesn't stand mute and inert before such unacceptable crimes," Francis said, "which constitute a worrisome erosion of the most elementary human rights." So far, the West looks away.

Nina Shea is director of Hudson Institute's Center for Religious Freedom and coauthor of "Persecuted: The Global Assault on Christians."