Why did Tamerlan Tsarnaev and his brother Dzokhar attempt to murder hundreds of ordinary Bostonians by detonating a bomb at the 2013 Marathon? What process of rationalization led them to think that it would be a morally appropriate to act on their murderous intentions? Tamerlan heard commanding voices, so his decision is explicable as part of a delusional process. But why did his apparently sane and well-adjusted younger brother do the same thing, why did he follow? Two stories have been told to explain the events. The first tells of a narcissist who strikes out against a world that has failed to live up to his inflated expectations of fame and glory; the second of two immigrant boys who are “radicalized,” by persons or forces unknown, and who decide to punish an America they believe to be cruel and corrupt. Neither narrative wholly convinces, but in analysing them, we can see a more complex and interesting story, of a disabled family that tries to solve its problems by faith, and then is sucked into the vortex of contemporary Islamist politics, simply because, in the West today, the politicized version of the faith is the one they were most likely to find, once they started looking. If they were doomed by faith, they were doomed equally by their own inability to imagine anything beyond the politics of fantasy, their failure to think through the dangerous ideas they were being offered as a faith.