Sam Killermann said this quote

With the evolution of Us came the evolution of Them.The original Them was anyone who wasn’t blood related — Them was pretty much everyone. Over time, as the number of people in Us got bigger, Them got smaller. Them now might mean anyone in any other country. This is a common Them in America, and a Them that only (light use of this word) consists of 95% of the world. Another common Them in America is anyone who isn’t Christian, which is a measly 68% of the world, or roughly 4.8 Billion Thems.In a relatively short amount of time, Us went from being a fraction of a percent of humanity and Them the rest, to some people experiencing an Us of more than two billion other people, far more than were ever alive at the onset of Us and Them.