So this is nonsense on a whole host of issues.
Are there Christian raids on Muslim kingdoms? Yes. Pirate raids, land raids, the works.
Is either side under full fledged assault at the time? Maybe the Byzantines.
Oh hey, @DineshDSouza, that bullshit Gibbon quote about the teachings of Muhammed being the curriculum at Oxford and Cambridge?
Universities are built up because of the 12th century Renaissance and scholasticism.
The Crusades were bad. Just because the people doing them at the time didn't think so, didn't make them good. You can't even pull a cultural relativism bullshit take on this--plenty of their contemporaries thought they were bad too.