Some religious conservatives want desperately to cast the current war as a struggle between Islam and Christianity. It is not. It is a struggle between Islam and liberalism (using 'liberalism' in its original meaning, not as a synonym for socialism). Liberalism has two great enemies: socialism in all its variants (fascism, marxism, democratic socialism, etc); and theocracy in all its variants (islamist, christian fundamentalist, etc).
In fact, properly understood, socialism is an outgrowth of Christianity. Its early proponents were explicitly Christian. Marx, ethnically Jewish but raised as a Christian, took the Christian ethics of self-sacrifice and gave them a pseudo-scientific base. So it's not surprising to see today's socialists acting like early Christians with their suicidal pacificism.
It is surprising, however, to see people who call themselves Christians ignoring the fact that Jesus was a pacifist who believed in forgiving one's enemies and turning the other cheek. The only time he ever raised his hand in anger was against a group of businessmen. Blessed were the poor, the sick, the meek, because they would find happiness in Heaven. The rich, however, would find it nearly impossible to get there. "Give your money to the poor and follow me." Is this what the religious conservatives believe? Not exactly. They practice a watered down form of Christianity, one which thinks this world is a Good Thing, rather than a steeped-in-sin, vale of tears--something to be enjoyed, rather than something to be resisted and overcome. In other words, they practice a liberalized form of Christianity, which has made its peace with capitalism and the pursuit of happiness.
Unfortunately, some of them think they can have their pursuit of happiness and their theocracy too. The islamists are not the only ones with medievalist fantasies, they are just more consistent and more radical. By envisioning the current war as a new crusade of Christianity against Islam, modern Christians are trying to reach back to the medieval period of Christian history. They don't want the Early Christian period, which was marked by the monastic movement and the rejection of all worldly concerns. It smacks too much of modern nihilism. Instead, they look back on the Battle of Tours, which marked the beginnings of a more wordly form of Christianity. When the Christians stopped the onslaught of Islam in 732 AD, they announced to the world that they would no longer turn the other cheek. They would fight, and they would martial the militant forces of the West to serve God. It was the beginning of the end for the Dark Ages, and it carried with it the beginning of the end for the practice of pure Christianity.
As Christianity attempted to control the world, it became worldly. The Church put its moral weight behind kings, and became a tool of state. It provided the state with learned men to make it more efficient. Those learned men would eventually remove it from the center of the universe and rip it assunder. Finally, tired of its armed theological battles, they would build a wall between it and the state, shrinking its sphere to the private world where it could be preserved only by compartmentalizing it, and adhering to it in a non-consuming, watered down sort of way.
Because Christianity is incompatible with life in this world. If society embraces life, it must eventually reject Christianity. If it embraces Christianity, it must eventually reject life. The mixture is unstable. It is either headed one way or the other.
It is good that Christians want to fight the war against the islamists. It is good that they want to preserve western civilization. They should understand, though, that what makes the west civilized is its love of this world. To love this world is an essentially irreligious viewpoint. It is certainly not Christian. It is not Islamic. It harks back to the Greeks and Romans. It is their gift to us, rediscovered in the Renaissance, and given fruition in the Enlightenment. Their legacy is what we are fighting for: science, individualism, ethical egoism, constitutionalism, rule of law, and humanism. That is what the islamists hate, and that is what we must preserve if we want to live.