The great trouble with NI is that the two communities just don't mix. They don't go to school together, as education is segregated. For us in the rest of Britain, a mixed school means boys and girls, but over there, mixed means Protestant and Catholic, which rarely happens.
Most of them live in segregated housing estates, so no mixing there.
A lot of work is also segregated. Few who are Catholic get a job at Harland and Wolfe, or the Police.
So you could easily be born, go to school and then go to work in Northern Ireland and never come across someone that doesn't share the same Faith as you do. Therefore your friends and associates tend to come from the same background as you, thus entrenching the same narrow political views that you have been brought up with.
People give their religious background away by their very names....There are few, if any Catholic William's and few if any Protestant Joseph's. They might live thousands of miles from each other, instead of yards apart.
I am not saying that Protestant Vicars or Catholic priests preach hate and violence from the Pulpit, but a lack of understanding and empathy does the same job.