The greatest evil

The greatest evil is not one action; a murder, a rape, a day's torture. It is a state of being. It is the merciless persecution of people by exclusion, insult, intimidation, theft, vandalism and maybe violence. Day in, day out, pursuing this agenda of destroying others' lives for their own twisted personal reasons.

It isn't triggered by rage or insult, personal greed or any sort of deliberate intent. It is sheer thoughtlessness. One might call it a lack of compassion, but it's done by people who in other ways can be very compassionate, and isn't the same lack of compassion one finds in deliberate crime. One might call it selfish, but it's no more specifically due to selfishness than almost any action is.

It is thoughtlessness, low-level malevolence and a lack of principle. A valuing of immediate emotional concerns over principled action; partaking of the widespread belief that small unpleasantnesses don't really matter, especially when done to strangers, even though the person who ought to judge such a thing is the person to whom you're being unpleasant.

Anyone can avoid murdering a person. Someone who commits murder either doesn't subscribe to the same moral principles as the rest of us, or else was provoked beyond self-control.
But those same supposedly principled people who subscribe to moral rules and most stridently denigrate a murderer for his momentary loss of control will often be the same people who break their own principles in small ways every day, and will nevertheless feel self-righteous about themselves and their lives.

It is this hypocritical self-righteousness that is the greatest evil in the world. I can cope with murderers who claim that the rules are pointless and don't apply. I can cope with criminals who regret their misdeeds. I despise all the everyday bigotry, bullying and other hypocrisy that the self-righteous never admit is wrong.

Given that it is thoughtlessness that leads to some of this, is there some way to correct it? Well, of course there is; make people think about things. But the problem is then how to make people think about everything when they have no natural tendency to do so. We can have awareness campaigns about bullying, racism, sexism, leaving litter on the streets and about countless more things or aspects of these large problems, but the more things people are reminded about, the more likely they are to forget something.
What is required is not 'awareness campaigns' for individual cases of unpleasantness, but a general rule. Coincidentally, something rather useful was first described by Immanuel Kant, a famous German philosopher. His categorical imperative says that one should judge the principle underlying the action and consider what would happen if everyone were to act according to that principle.
In a democracy, voting might be a good example of an application of this principle. There is no commonly accepted immorality in not voting, but Kant's categorical imperative gives us a new analysis: we consider what would happen if everyone were to feel too lazy to vote and we realise that anarchy (or, if almost everyone were too lazy, rule by a very few people who had taken advantage of everyone's laziness to vote themselves power) is undesirable. We are therefore obliged to vote.
However, Kant's emphasis on the principles underlying an action is most relevant here. People will frequently judge that a little insult here or a push or a shove there are insignificant, but it is not their place to judge. They, when questioned on the subject, usually admit that the action was bad, but that it didn't matter. If we could only teach people to think about principles and not consequences then we might eliminate a lot of the little evils in the world that all add up to a lot of nastiness.
When a man owes £1, and decides not to pay the debt because it's insignificant, he is stealing. When he queue-jumps, he is cheating. When he insults someone, it can hurt, it can be spread and it can sow little seeds of doubt about someone in others' minds. If it was meant to be insignificant, then it was better unsaid. Bullies need to think what the world would be like if everyone were to bully those they could: we'd have no social cohesion at all, and we'd have networks of force and dependence. Without the social fabric of society, the bullies would either be petty-minded thugs living in perpetual fear of someone killing them in order to pre-emptively save themselves, or else weak dependants being abused by other thugs.
Queue-jumpers face a similar problem: if no-one had any respect for the accepted method of rationing demand to limited resources then we'd have great heaving masses at every counter. The sharpest elbows and strongest shoulders would win (I'm blessed with both, thankfully).

But this is just repeating what I've said before. What really matters is that the small things do matter. Nothing can be assumed to be insignificant. If it's wrong, it's wrong no matter how small it appears. £1 to one person might be a couple of minutes' work. To another it could be a day's pocket money.
We should always judge based on our principles, not on our feelings. I have heard people excuse themselves because they had been stressed earlier, had a bad night or just couldn't be bothered. Laziness is no excuse; nor is grumpiness, PMS or any other stress. The spreading of small evils is something that almost everyone does, and it is the false justification through irrational arguments that drives me utterly batty. When we talk about murder, we don't say 'oh, I did it because I slept poorly'.

What we do find, however, is that people say
"I just couldn't deal with it any longer. (S)He'd been going on at me for years and that [whatever it was] was the last straw."

Just imagine if every time someone felt grumpy or lazy, instead of taking it out on other people they controlled themselves. Would those poor benighted murderers ever reach the snapping point? If other people stopped the bullying and the cheating, would there be any gradual build-up of rage?
Are the 'great' evils strange manifestations of the devil, or could they perhaps be partly a result of everyone else's little evils building up in someone?

What are the similarities between a murder and an insult? They both require a lack of self-control. They are both wrong. Neither becomes right because of personal opinion. If you do something to someone else, it should be with his consent.