It is quite difficult to give the accurate answer of this question. Some terrorists are fighting for their religion, some are for their independent country, some are against the social injustice and some are here for money. The one of the major reason which comes out is religious intolerance. There are some religions in the world which are feeling insecure in present times. To put forward their voice they are using the way of terrorism. They are seeing the world as threat on their religion.

The main reason behind their taking the extreme step of terrorism may be that they are finding themselves behind the world. They are seeing the advancements in the world as potential threat against their religion. They are fearful that there followers may discard them and chose the other path. Therefore they are treating it as direct attack on their religion. Second reason behind the terrorism is fight for independent countries. These fights are also to some extent are linked with religious sovereignty and rather the independent states.

People did not want to live with the people of other religion because of the earlier bitter experiences. They thought that by living in their own religion they will be safer. The fight for Kashmir and Philistine are of this kind. Third one is fight against social injustice. There are many countries in the world where still social system is in bad shape. These situation leads to unrest in people and they chose the way of violence. Fourth is a new category which has emerged of people who can do anything for money. There only religion is money and they can even kill some one for this.