The first few years of a child are spent surrounded by the walls of the house and protected dearly by the family. He enters a world which comprises of his mama, papa and sister.
Ever wondered why this toddler dreads going to school? One of the reasons is that he dreads losing the protection of the family. He sees his school bus as an Unidentified Terrestrial Object that would take him away from his world. He conceives his new school as a new world with new unknown faces and strange people.
Yet, his playmate in school might find it a wonderful new world with many new people to meet and newer friends to make. This child is more likely to grow independent and open to new things unlike our cry baby. This child's world is more likely to grow bigger sooner than our cry baby's world.
Not all of us are good at accepting new people and their newer different ways of behavior. We tend to bond with a small group of people around us whom we select based on our own judgments. The rest are conveniently disowned as different, not-our-kinds, weird - Aliens. They form the outer world not warmly welcomed into our own world.
Groups are formed in order to provide support and protection to the members. But I doubt if groups formed out of religious basis do just that. When religion is used as a tool, more often than not, it takes the form of paranoia. I have been an eye witness of college riots among students of rival religious groups and those were enough to keep me from joining any such groups myself.
Paranoia surpasses limits in the part of the world I hail from. The apparent logic behind distrust for other religions and groups is the genetic make of the members of those groups. Different religion unquestionably implies different genes, different biological make-up and therefore, 'different' humans. Marriages, therefore, can happen only among the followers of the same religion.
As noted by researchers of the World Values Survey, culture strongly influences how a person sees the world around him. Collectivistic cultures of Istanbul, Turkey, Saudi Arabia, Muscat, and Oman stress interdependence between people and the notion of group goals. Cooperation is sought with people inside the network which is organized along family and friendship lines; everyone else is an outsider.
Individualistic societies, on the other hand, view each person as an individual and value individual goals. These mores are more prevalent in wealthier, market-based democracies where group boundaries aren't very important. Cooperation with unrelated strangers becomes necessary in such societies. Accordingly, members of the capitalist democracies are more likely to accept strangers into their societies and are actually kinder and gentler than more traditional economies.
World is a small place, belittled by our own prejudices.