They were protesting the G20 summit because they don't believe in capitalism. This is not out of the ordinary. Anarchist have been against capitalism since their conception. However, the odd thing is that this protest began with a reverend preaching about "not accommodating the devil". Exactly who is the devil? It's must likely capitalism. But since when have anarchists and religion worked together? As far as the all-knowledgeable wikipedia, anarchism and religion don't mix. After being faced with this evidence, I must disagree with wikipedia, anarchism and religion are perfect for each other. Both are useful in a time of crisis, and isn't the U.S. in one now.
We haven't seen this many protests in the past because people were employed and had jobs to show up to. With the current high percentage of unemployment, Americans must find something to occupy their time with. Protesting seems to be the perfect time consumer. Why? Well because protesting is the same as complaining. Something that we are all guilty of doing when things aren't going the way we want them to. As Americans we complain about high gas prices, interest rates and taxes. However, very rarely do we do something to cure us of our ills. I do not approve of violence, but I have to say that I am proud to see Americans not just complaining about their problems. They are taking action to improve America. Now all we need is for moderate Americans to would get involved and fight for helpful non-radical improvements.