This show has some gruesome imagery, and may lack depth in some of its characterizations, but it is a weirdly engrossing thriller, and it succeeds for those with the stomach for such things. The writers try hard to provide some of the motivation for the unspeakable crimes committed by the Followers, but most of the emotional impact comes from the interplay between Kevin Bacon's damaged FBI ex-agent Ryan Hardy, Natalie Zea's Claire Carroll, the show's only well-balanced character, and James Purefoy's Joe, who is characterized as a serial killer, but who is so much more. I enjoy that the FBI team tracking Joe is composed of such baggage-laden individuals, each with a propensity to act impulsively in their pursuit, giving the plot an edge of unpredictability. One ploy that's getting a bit tired, though, are repeated approaches by supposedly sympathetic Followers, who then turn to lethally attack the FBI team when they have let their guard down. But it's Joe's character and actions that provide the show's greatest strength and its greatest weakness. His apparent charisma as a teacher is mirrored by his diabolic power and mind-control as recruiter of murderous followers. His use of pre-existing fringe networks as talent pools and their organization as an instrument of his unfolding master plan is ingeniously shown, as well as all the tech-gimickry of secret websites, untraceable sat phones,etc. The weakness, for me at least, is the simple question, "who's paying for all this?" Joe is a college professor, failed novelist, and a cult leader. His organization appears to have the military armament, tech resources, and funding of a sponsored terror network, just like on 24 (which would have had oil money, blood diamonds, or a drug smuggling cartel behind it).
His Followers are many, but no one has been shown to be his financial "Angel". But if you can set your rational skepticism aside you can enjoy a weekly occurrence of white knuckles gripping your sofa arm or that of anyone you're with.