Islamic mandate for beheadings?

Interesting paragraph from Jeff Jacoby's column today in The Boston Globe. ''There is more to the Islamist passion for decapitation than psychological warfare and a hunger for notoriety. There is also Muslim theology and history, and a mandate going back to the Koran. In a 2005 study published in Middle East Quarterly, historian Timothy Furnish quotes the famous passage at Sura 47:4: 'When you meet the unbelievers, smite their necks.' For centuries, Furnish observes, 'leading Islamic scholars have interpreted this verse literally,' and examples abound throughout Islamic history.'''