Headline-grabbing stories about a British-based Muslim academic's public support for "martyrdom" last weekend missed a key detail: His mentor and frequent collaborator is a high-profile scholar who has been consulted repeatedly by the FBI, Professor John Esposito of Georgetown University.

Mr. Esposito has long courted controversy — most recently when the Georgetown-based center he founded in 1993 accepted $20 million last year from (and took the name of) a notorious Saudi prince. Yet, the professor has somehow been able to maintain a relatively high reputation in academic and government circles alike.

That Mr. Esposito is still largely respected owes to the subtlety of his apologism. He acknowledges that there is radicalism in Islam, and he generally avoids defending the likes of Hamas and Hezbollah. Even as he argues for engaging Islamists, he does so without overtly endorsing their worldview. But Mr. Esposito skillfully downplays the threat posed by radical Islam, and as demonstrated by his close affiliation with Azzam Tamimi, who told a massive crowd in the UK on Sunday that "dying for your beliefs is just," he willingly associates with avowed cheerleaders of Islamic terrorism...