More than a decade ago, counterterrorism expert Rita Katz began browsing white supremacist and neo-Nazi forums. The hateful rhetoric and constant threats of violence immediately reminded her of jihadist militants, but law enforcement and policy makers barely paid attention to the Far Right. Now, years of attacks committed by extremists radicalized online-including mass murders at a synagogue in Pittsburgh and mosques in Christchurch, New Zealand, as well as the Capitol siege-have brought home the danger. How has the internet shaped today's threats, and what do the online origins of these movements reveal about how to stop them? In Saints and Soldiers, Katz reveals a new generation of terrorist movements that don't just use the internet, but exist almost entirely on it. She provides a vivid view from the trenches, spanning edgy video game chat groups to mainstream social media platforms to what ISIS and Far-Right mass-shooters in El Paso, Orlando, and elsewhere unwittingly reveal between the lines of their manifestos. Katz shows how the online cultures of these movements create today's terrorists and shape how they commit "real world" violence. From ISIS to QAnon, Saints and Soldiers pinpoints the approaches needed for a new era in which arrests and military campaigns alone cannot stop these never-before-seen threats.