Will there always be an "us" and "them"? If so, is that a good thing?

There are so many oppourtunities these days to pick an "us" and a "them": libs, cons, Reps, Dems, gays, women who want abortions, illegals, Christians, neocons, Muslims...etc., etc.. I know being in (or against) one or more of these groups can help give us a sense of identity, belonging and serving a greater purpose, but are we really getting any closer to "defeating" any of these groups or are we just finding other people to blame for our problems? What would we do without "them"? I beleive it was Jung who said "What we resist persists.". Do you think the wars on poverty, drugs and terror have made those social woes better, worse or kept them the same? Or do those wars serve to absolutely ensure that those problems always remain with us?