Why Do Like-minded People Fight with Each Other?

The brahmin Aramandanda approached the Venerable Mahakaccana, exchanged in friendly greetings with him, and asked him: “Why is it, Master Kaccana, that khattiyas fight with khattiyas, brahmins with brahmins, and householders with householders?” 

“It is, brahmin, because of attachment to sensual pleasures, adherence to sensual pleasures, fixation on sensual pleasure, addiction to sensual pleasures, obsession with sensual pleasure, and holding firmly to sensual pleasures that khattiyas fight with khattiyas, brahmins fight with brahmins, and householders fight with householders.” 

“Why is it, Master Kaccana, that ascetics fight with ascetics?” 

“It is, brahmin, because of attachment to views, adherence to views, fixation on views, addiction to views, obsession with views, holding firmly to views that ascetics fight with ascetics.” 

from In the Buddha’s Words, An Anthology of Discourses from the Pali Canon