Understand Christ also advocated nonviolence But then why his followers indulge in Voilence?

Very simple answers; man has free will. It is a decision of the man to decide what path to take. The examples you have used is when man, not Jesus has twisted his teaching and brought pain on to others. I myself am a keen reader of the teachings of Jesus and I believe it has made me a better person as I am more likely to help someone in need as I see everyone as my Brother and sister. It is also obvious many leaders have not listened to his teaching as we are in vicious circles of war at the moment.