One of the easiest ways to maintain the way you feel about the "others" (whether that be in religion, politics or war) is to never let them become real people to you.
As long as they are "the trinitarians", "the Iranians", "the terrorists" etc then we can lash them with impunity.
But when we meet, when we see who they are as a person... then it can sometimes make that harder to do.
And... then again... sometimes it is easier than ever.
Depends on the person.