Europe's below-replacement-level birthrates have created situations that would have been unimaginable in the 1950s. As recent demographic studies show, by the middle of the 21st century, 60% of Italians will have no personal experience of a brother, a sister, an aunt, an uncle or a cousin; Germany will lose the equivalent of the population of the former East Germany. Europe is depopulating itself in numbers greater than at any time since the Black Death of the 14th century. When an entire continent, healthier, wealthier and more secure than ever before, fails to create the human future in the most elemental sense — by creating the next generation — something serious is afoot. Demographic vacuums don't stay vacuums; they get filled — in Europe's case, by Islamic immigrants. Europe's effort to create a tolerant, civil, democratic civilization by cutting itself off from one of that civilization's sources — Jewish and Christian convictions about the dignity of the person — is likely to fail. If Europe rejects what Pope Benedict XVI on Wednesday called its "unrenounceable Christian roots," the results are likely to be grim for those committed to decency, human rights and democracy.