I think that part of the key to understanding a group of people is to understand exactly who it is that they contrast themselves to. The obvious differences are too trivial to mention but the more subtle ones are vital to understanding a groups collective identity.
If you were to ask a Hassidic Jew in Boro Park how he perceives himself, and with whom does he contrast himself, there is a good chance you will hear that he sees himself as a Hassidic Jew as opposed to either, a misnagid (a non-hassidic ultra-orthodox Jew), or perhaps his modern orthodox cousins in Flatbush. Chances are he will not say that he sees himself as a Hassidic Jew as opposed to, say a black guy. You have the same situation with a Syrian who perceives himself as an Arab, but not like those Saudi Arabs. Or the immigrant from Ecuador who sees himself more like everyone else but different from the Cuban or Puerto Rican.
The tendency on the part of outsiders to make generalizations about groups that are too broad is the biggest giveaway that the outsider is indeed way outside.
There are Russian immigrants and there are immigrants from Moscow, Carpathia, the Ukraine, and Kiev. Failure to perceive the differences will result in a complete misunderstanding of the motives of some individuals or communities. Sunni, Shi'a, and Alawites will just never get along, despite the fact that to the outsider they are all Muslims.
To presume that Christians are anti-abortion because Catholics are, is to not understand Christianity. The insider will listen to someone talk and then have a flash of insight wash across his face when he discovers that the Italian he is conversing with is really Sicilian.