It's not enough to have things in common. The point the previous post make is that it requires a common enemy to forge unification as strong as the US and even here there are talks about some states wanting to go independent from time to time.
Without this external factor it's hard to find something to really feel the same about.
And yes. Leo Strauss was of that opinion and you will find a whole suite of argument that talk about how the middle east became the new enemy out of need rather than actual threat.
This was part of the PNAC (Project for New American Century) which identified the need for a new enemy after the fall of the wall.
Now whether they were actually successful is another discussion but it was part of the Bush administrations fundamental belief as several of it's key members where students under Strauss.
Without this external factor it's hard to find something to really feel the same about.