To Americans, "nation" is often another term for state or country. But to much of the world, "nation" refers to an identity that may or may not be coterminous with an established state. It is only recently, for example, that many of the nations of Europe have come to have states to call their own. This means that the word "nationality" also means much more and less than "citizenship" to many peoples. The people of the Austro-Hungarian Empire, as well as those of the Tsarist, and later Soviet state often required that people identify themselves by nationality, including the widely dispersed Jewish "nationality". To people using the word in this sense, political units are "states", peoples are "nations". To Americans, of course, "state" refers to a subunit of an independent country or nation. The significance of this discussion is that communicators must be clear what audiences they are addressing before they use words in this group.

"Religion" can be understood as a "faith" (see accompanying discussion of belief-words). But in our context here, it is better understood as an affiliation or identifier. In many contexts and to many people, one is seen as inexorably and eternally a member of the religious group he or she is born into — even, if one loses or renounces the faith associated with term, or even formally joins a different group. In such thinking, once a Muslim, always a Muslim (as many in the FBI no doubt believe).

"Ethnicity" and "ethnic group" are taken from anthropology where they refer to cultural identity, but this meaning is often intertwined with racial identity in common usage. They are brought up here because they are often used as an alternative way to refer to the identities discussed above. Ethnicity also has the broadest meaning, in that it may refer to a distinctive group that has for whatever reason (for example, relatively small size) not generally been thought of as a religious or national group.

The habit in the ethnography of an earlier generation was to refer to relatively small groups of preliterate people as "tribes". Sometimes the group identified was well-organized and structured in a manner analogous to a "state", but at other times the designation merely meant a group of people united by a common bond such as language. Such a "tribe" might not readily have been recognized by the people said to constitute it.

A "gang" is a small organized group created to further the objectives of its members. Sometimes such a gang is an evanescent formation of teenagers. Sometimes it is a well-organized group persisting over many generations. One general distinction from the foregoing identities is that historically gangs have consisted primarily of males.

These terms have been juxtaposed on this page to suggest that these terms actually have more in common than is often supposed. The Catholics and Protestants of Northern Ireland and the Muslims and Jews of Palestine are not at one another's throats because they have different religious beliefs. Many of the participants would be hard pressed to explain what the differences are. Jews and Muslims, for example, are religiously, linguistically, and racially, extremely close. Symbolically, however, they are sworn enemies, much as the clans of ancient Scotland or the "Gangs of New York".