From George Weigel about his new book, Faith, Reason, and the War Against Jihadism: A Call to Action. (edited and numbered by me)
The Pope accurately described the twinned threats of faith detached from reason,Mitt Romney touched on this theme in his Dec 6, 07 "Faith in America" speech.
 so that you can believe that God commands you to do the irrational, like blow up the World Trade Center, and reason having lost faith in itself,
 so that the West no longer has the capacity to say here is why religious freedom, separation of religious and political authority in a state, civility, tolerance, democratic persuasion rather than coercion, here is why these things are morally superior.
Those are the two sides of the great culture war in the world today, and the Pope hit it right on the head.
I have visited many of the magnificent cathedrals in Europe. They are so inspired . so grand . so empty. Raised up over generations, long ago, so many of the cathedrals now stand as the postcard backdrop to societies just too busy or too 'enlightened' to venture inside and kneel in prayer. The establishment of state religions in Europe did no favor to Europe's churches. And though you will find many people of strong faith there, the churches themselves seem to be withering away.
Infinitely worse is the other extreme, the creed of conversion by conquest: violent Jihad, murder as martyrdom... killing Christians, Jews, and Muslims with equal indifference. These radical Islamists do their preaching not by reason or example, but in the coercion of minds and the shedding of blood. We face no greater danger today than theocratic tyranny, and the boundless suffering these states and groups could inflict if given the chance.