During the 1990s, perhaps 150,000 people perished in the hellish violence that raged over the Balkan peninsula. Al­though the conflicts were largely defined by ethnic differences, religion played a critical role in the three-sided war be­tween Orthodox Christians, Roman Catholics, and Muslims. Armed gangs would burst into a house and demand that residents make the sign of the cross. Your life could depend on whether you made the horizontal bar from right to left (Orthodox) or vice versa (Catholic). Across Kosovo and Bosnia-Herzegovina, ancient places of worship were desecrated and their artistic treasures vandalized.

After such horrors, it might seem unthinkable to find signs of hope in the region’s religious life, but some forceful individuals demand our attention. One is Mustafa Cerić, the Islamic grand mufti of Bosnia. In the worst of the violence, his faith not only survived but grew and broadened. As he said, “When you are faced with death and when you see that humans do not help you, and you are left alone for four years in besieged Sarajevo, therefore you cannot live alone, you have to seek some help.” He has worked diligently to promote understanding between Europe’s Muslim, Jewish, and Christian leaders.

Mustafa Cerić speaks force­fully to European Muslims, who face the twin seductions of secularism and Islamist extremism. Muslims, he says, must reject any view that “the only hope is in the Muslim past as a way of life and a goal of history.” In words that apply across religions, he urges Muslim migrants to Western Europe to follow three fundamental laws: learn the language of your host country; obey its laws; and try and do something good for that country.