"Stabbings, bombings, riots and even within governments" is nothing new. People have been ravaging others without good reason for ages. The vast majority of wars worldwide are caused through religious beliefs. Even before God was invented, whole portions of the world would try to devastate other parts.
The atrocities performed by ISIS are nothing new either, it is just that even last century, electronically distributed news was not so widespread so the world wasn't so aware.
If anything, the present world is in tighter control than before. It is not so long ago that a religious killing was always followed by a retribution killing etc. etc. Now, the 'developed' world has so many PC rules that we are mere puppets at the mercy of others.