In today's culture, it can be tempting to get angry over the amount of injustice we face. It seems justice simply can't be done these days. This anger, though in many ways justified, is ultimately the result of being too worldly minded.
The Bible describes the people doing these bad things as a vapor. They're not going to be here long, they're going to face God eventually. So how should we react? The anger we feel is justified, and indeed is shared by God (Psalm 7:11), but really, we need to consider that one day this will all be put right, and think about what, exactly, that means. If the wicked refuse to repent, they are experiencing all the Heaven they are ever going to get. Do we, as Christians, really need to be angry with them?
The Bible tells us that in Heaven, this world won't even come to mind (Isaiah 65:17). You're not going to remember the injustices of this world. But the lost will. Every sin they have ever committed will weigh on them forever. The way I like to think of it is that in 20 billion years, I'm not going to remember the time my Christophobic classmates kept harassing me while I was trying to complete my coursework, but they certainly will. So, rather than being angry with the wicked, let's leave that to God. Instead, let us encourage them, beg them even, to repent and get saved.