In some places, there's the concept of one religion, one truth. In the Muslim world, there's the notion of Allah. The Western, multireligious modern society is some kind of a challenge to this. These, I feel, are the main causes [for terrorism], and, when combined with lots of anger and frustration, cause a huge amount of hate.
Spend 5 minutes at the beginning of each day remembering we all want the same things (to be happy and be loved) and we are all connected to one another.
Cultivating a close, warmhearted feeling for others automatically puts the mind at ease. It helps remove whatever fears or insecurities we may have and gives us the strength to cope with any obstacles we encounter.