I’d have to concur with FightingFat. Islam was the colosus at the time of the first crusade, so it could definately be argued that it was a Christian fight for survival. Some of the later crusades were counter productive and much shakier morally.
Today, Christianity is the dominent world religion and, of the percentage of the world that does practice Islam, the vast majority do not endorse violence or jihad.
The violence we have today seems more related to oil than ideology. For example, the House of Saud has put about $70B into extreme Wahabism (to basically keep the throne). So it should be no surprise that the 9/11 terrorists were overwhelmingly Saudi. But we need the oil, so the country funding terror and providing terrorists is still a “good friend”.
Such a good friend that we sell it large amounts of high tech weaponry. Arming an Islamic state to the teeth, while it gives big chunks of oil revenue from us to religious extremists, doesn’t seem to have a basis in Christianity. It is wholly pragmatic. So the violence related to it should probably not be viewed in purely religious terms.