If it is not abundantly clear to you by now that violence begets violence than actually you 'deserve' the guaranteed misery that comes from it.
So now that people are supposed to believe that some Paris attackers were refugees we can safely assume it will lead to great tension between people in Europe. Add to that all the new laws, state surveillance and other 'security' measurements which of course only will enhance this tension. People simply shouldn't allow themselves to be divided nor resort to violence for it only will beget more violence, don't you know? Can we stay calm and effectively tackle the 'terror' problem? We will see in the very near future and I certainly hope so but at the same time don't think so.