In the Lebanese drama ”The Insult” an Oscar nominee, a relatively minor interaction between two men mushrooms into a national tumult in which Christians are pitted against Muslims, each side proclaiming its victimhood with increasing violence. In its sensitivity to both men’s subjective experience of the incident, Ziad Doueiri’s movie is everything this critic has wished aloud for: a humanist exploration of racial animus in which huge cultural and historical forces manifest themselves in the smallest of exchanges, and in which tit-for-tat blood feuds stand revealed as cries of weakness instead of shows of strength.