The Crusades are often derided in modern European multicultural sensitivities. It is forgotten that they were wars of retaliation, that Islam invaded historically Christian and Jewish lands *before* the Crusades. But did the original Islamic invasion preserve a remnant of Hellenistic thought that became our modern scientific era, only because the Crusades took it back before the anti-science Ottoman Empire had a chance to destroy it?
If your education is infected by "liberalism", you might want to read this debunking first to see where the author of the article is coming from.
The Real Significance of the Crusades | Crisis Magazine: