It is very common for a group of people to define itself by way of negating an idea or a way of life. A family relation or physical proximity may define kinship within relatively smaller groups; but when it comes to defining a binding identity for a nation, a common antagonist (usually an idea) is usually adopted. And just like the US needed communism (even though it had a few major positive ideals it could use) to overcome partisanship, and Arab nations use Israel and the US to unite their people behind a different cause than overthrowing their oppressors, we need a threat to unite us as a nation so to avoid splitting into smaller "anti-defined" factions such as secular/orthodox, leftist/rightist, etc.
I am sure, like me, other readers will regard humanism as a strong enough ideal to bind nations together, but alas, we are only an overwhelmed few in the greater scheme of things. Often times it seems to me that the only possible way to unite all of us behind any single identity (humans?) would be the fear of alien invasion...