Sweetie, they've been killing each other for thousands of years. But don't worry, they'll be back to killing infidels next week.
If they associate with the infidels in any way, shape or form, they are guilty by association and subject to their wrath. Two translators I worked with in Iraq (both of whom are dear friends and with whom I stay in contact with via weekly emails), have had their lives threatened several times for working with the Coalition in Iraq