A little more about identity...

Another thing to notice about identity is the role it plays in the enlightenment notion of equality (as in, "everyone is equal"). In order to derive that kind of equality, we deliberately factor out precisely the properties of a person that constitute that person's identity--the person's race, religion, creed, lineage, etc. It is not that the Christian and the Muslim are equals qua Christian and Muslim, but rather, they are equal qua human beings, independent of whatever religious beliefs they happen to subscribe to.

And, in fact, you see precisely this process of "factoring out" take place in Rawls' Theory of Justice, with the whole original position thing and it's 'veil of ignorance' (a good, brief summary of the original position can be found here).