It's the bad choices that people make. We have the free will to choose to follow good or evil. And they choose evil. We just have to pray for them in hopes they realize what they are doing is wrong and would put an end to it.
One word: Disagreement.
There are religious and scientific conflicts for instance, that can branch out to so many more conflicts. First of all, humans are naturally aggressive. Our biggest predator is ourselves.
It's scary to think about, but it's nothing but the truth. We don't have wars against insects or lions, do we? We are surrounded by violence (video games, television, etc) that may influence us because we deem it "cool" and "awesome", therefore we must do the same. I'm not saying these things are bad per se, but are they really ideal?
I wish we, as humans, would just get along. I think people should understand that others have different mindsets and ideas and accept that. What is the point of fighting for it if it's not going to change - ever?
To put it simply, we are surrounded by people who disagree, think differently, people who seek their influence from other sources around them and act upon them, all these things. It befuddles me how careless we truly are.
Unfortunately, there are plenty of reasons why the world is full of violent acts, but I would suggest that many of them occur due to a feeling of oppression.
When an individual, or a group of people, feel that they're being oppressed, they often lash out in an attempt to make a point. These actions aren't always understandable, but that's the primary basis of lots of the world's violence.
Having said that, there are plenty of other reasons why violence is so prevalent in the world today:
- Politics - governments often clash over many different issues, and if left unresolved, can lead to conflict over time. Sanctions on weapon construction has been known to be an issue within this sector.
- Religion - clashes in religious beliefs has been a breeding ground for violence for years. This is often exacerbated by extremists, who act out in a way that the rest of the community disapprove of.
- Envy - some people are very jealous of what others have in life, and sometimes this can cause them to go to desperate measures to obtain the same thing. This can lead to violence and other crimes.
- Lack of empathy - there is a small selection of society that seems to enjoy the suffering of others. Think of the people that randomly attack strangers in the street for no reason. There is nothing to gain from this situation other than the hurt of another human being. Sadly, most of these people are a lost cause.
As you can see, there are plenty of reasons why violence is so prevalent within the world today. There are certainly loads of reasons that I've missed out, too.
The best thing we can do to combat violence is to make a stand. By treating your fellow human beings with kindness, you're balancing the awful acts that we see around the world. Hopefully there will be a time where violence is simply a thing of the past, but for now, it seems we're stuck with it.
There is violence in the world and it causes so much sorrow, it is caused by the sin that happened in the Bible with Adam & Eve.
There are many reasons, like those stated by the previous answers. However, there is one simple answer: It is human nature to cause violence. People may try to stop it, or they can just accept it.