These people have been living in hatred for thousands of years. There is no blame to be laid upon now, except perhaps to their own ancestors.
These people are taught from child birth to hate the other side because that is what their parents taught them.
How does one compete with thousands of years of tradition? You can't change it. You can't tell them that they're wrong and they should learn to just live in peace.
It's not going to change just because the Americans hold a military 'peacemaking' presence in Iraq.
Things are never as simple as we, the western world, want them to be.