While I don't believe wrath or anger is the worst of the sins, it's probably the deadliest, depending on how you measure that, of course. Sure, if you count disease or car accidents, they'll kill more than murder, but those can't usually be directly attributed to one of the deadly sins.
Obesity is quite the killer, though.
Gluttony is bad even if there was a miracle cure for obesity. But wrath creates violence, and that is a direct cause of death. So, in my opinion, wrath is the deadliest of sins. Not only that, it's probably the most obviously bad. There's really very little upside to wrath.
Wrath, like gluttony and lust, are really about discipline, or a lack of it. It's about losing control and doing something you shouldn't. Wrath stands above the others, though, because of the harm it does to other people.
What about punching something?
Sure, when someone flies off the handle, he or she might hurt themselves or destroy their property, like a kid who gets beaten in a video game kicking his computer, but usually that anger is directed at someone else. Hurting yourself is one thing, but hurting others takes it to the next step. That's why wrath is in the top worst of the deadly sins, in my opinion.
Why isn't it the worst, then?
Well, we do still have two left, that's true. Wrath is the most primal of the deadly sins, but that makes it something we can typically see coming in others. It tends to be more obvious. Yes, it's brutal when it comes out, but it can often be restrained. Sometimes not, of course. It the first of truly awful deadly sins. I'd much rather lose a loved one due to envy or lust than because of wrath.
We all have that rage within us. How do you control your temper? Does counting to ten help? What do you think of my list so far? Let me know in the comments!