It's a bit different to what I originally thought. The idea is that our identity, or some important aspect(s) of our identity is fixed at birth and we cannot change it. He describes this unchangeable element as some kind of "essence". The author considers this idea to be negative as it means that people will never be able to understand others who are different.

this is the paragraph In his book In the Name of Identity, Amin Maalouf explores how violence can erupt between different groups of people when they limit the definition of their identity to only one facet of their being. This belief that an individual is defined essentially by their nationality, race, language, or religion “presupposes that ‘deep down inside’ everyone there is just one affiliation that really matters, a kind of ‘fundamental truth’ about each individual, an ‘essence’ determined once and for all at birth, never to change thereafter” (2). This, Maalouf explains, is “a recipe for massacres” (5). A Christian who grew up in Lebanon and later moved to France, Maalouf has personally felt the conflict that can exist between different elements of a person’s identity. Quite simply, he writes that people “often see themselves in terms of whichever one of their allegiances is most under attack” (26). Recalling the nights he spent with his pregnant wife and young son in an air-raid shelter, Maalouf knows that “fear might make anyone take to crime” (27).

Would you please write it again!!!

By the way, it's "Could someone please explain this to to me?"

Could you please provide more of the passage?