Why ISIS is Islamic and why it matters

The question of the relationship to Islam of radical Islam in general and ISIS in particular has never struck me as perplexing. Radical Islam is the radical strand of Islam, and ISIS is an extreme version of the radical strand. Its actions are consistent with portions of the religion’s core text which are founded on the conduct and preaching of the religion’s founder.

You don’t need to be a scholar of Islam to figure this out.