Violence acts, in its many forms, has psychological or and physiological reasons. many deeds of continued violence, specially serial criminals, are driven from pyschological or physiological anomalies or predispositions, and it happens when it gets into overload (psychological). its not solely because some people need to make statments and call attention to something that they do it, although its not the right way has you mentioned. for the other cases, they can not help it, its out of their control, and need guidance. others just do violence because they simply want to, have been educated into that and want to be important in their comunity or a certain group.

sexoholics have an organic addiction, its not crime only if they start raping people right, but they are addicted to the adrenaline shoots they get from sex, not just having sex by itself, it's the shoots. Post traumatic stress or obssessive compulsive bahaviors can trigger violence, as a self protectant mechanism. a person who has high levels of adrenaline released in the body are more predisposed to do it also. Sexual sadists only derive pleasure in harming other people, although it might be umcomprehensable to normal people, its their normal conditon. and they are void of all normal human feelings, cant feel sorry, regret, remorse, love, attraction... again, the biology in action, a certain part of the brain, not to get technical, that triggers emotions and spread it, releasing it in chemical messengers all over the brain, exciting it. So those subjects have an anomaly on that, they might want to feel something and push it, but they cant. so they derived pleasure in other way...
Bio-psycho-social is the key. Biology turns them into a weapon, psychology targets it and social interactivity pulls the trigger.

back to the topic here in question, of course that man didnt have to comit violence, it was just a radical way to undermined his deep feelings of greif, trying to kill his faith. but when the ends breaks loose, and his state is unveiled, although he have done bad things in the process, you must still feel sorry for the guy, or you're not human. that was nasty and disturbing. it became aware to me, that i still have some submerged inside, because i felt sorry for "the possibility" of such scene. still, i havent much left...

see the video. its fictional, but yet no that fictional. a lot of fiction is based on reality, and thats a perfect possibility for the "real world", with 6 billion on the planet that must happen somewhere. alike this.

anyhow its a great scene.