You’ve heard “Don’t Kill.” But I say Don’t even be angry.
You’ll use “Don’t Kill” as a shield to protect your seething rage. Don’t do that.
Before you go around like you’re such a holy person, think, “Who’s got anything against me?” Try as best you can, to the extent that it’s possible, and reconcile with them. Way better to do that hard work than to go around like you’re hot stuff meanwhile you’ve got all these hits against people out there.
That’s what the hypocrites do and you’ve got to be better than them.
Maybe you’re right and no one’s got anything against you—not very likely, but even so—quit going around like you don’t stink. You stink. Clean yourself up. And in doing so you’ll be helping out lots of other people along the way. And if it turns out someone’s right who’s got something against you, you’re now in a much better position to fix it than you’d be if you were going around like you’re God’s gift to the planet. You’re not.
At Trent the Church used Jesus' “don’t kill…reconcile” from the sermon on the Mount to teach that even sins against the “last two precepts of the decalogue” could be counted as mortal. How often do we defend ourselves with, “I’m basically a good person, I mean, I haven’t killed anyone?” It’s a weak defense. Even if your sin is merely in the heart, it’ll get you. Cut it out.
(More later on the sin-of-anger vs. the passion-of-anger/virtue-of-meekeness.)