This country COULD be united, if we silenced the traitors within. But they are smart, and captured the influential institutions years ago. There, they can dig in and fight a rearguard action that will cost lifetimes to uproot. Time is on their side, as the ignorance they spawn seeps in and pervades our culture.
We've got them contained for the time being, but we must work actively to DESTROY them, or they will continue to infest us.
That's too easy an answer.
The problem is not "the traitors" per se, but rather those of us who are not "traitors," but who don't understand and therefore cannot properly defend ourselves and our institutions against decay.
It's very hard to be vigilant -- it's not only hard work, but it also requires one to say and do things that seem "mean" to others. In fact, I think most of our problems stem precisely from a very poor understanding of what "mean" really is; and what "fairness" is really all about. We're driven by the emotions of the moment, rather than a willingness to understand and accept the long-term the consequences of our actions.
Likewise, it's very hard to serve the community -- it often requires great sacrifice, and a lot of hard work. And thus we allow perversity to be normalized; and we surrender our institutions to those who are driven by something other than a desire to serve the greater good.
One thing I think confuses people making the historical analogy with Rome is the speed at which things happen today. We only really attained superpower status 60 years ago, and this business about being the only one is brand new still.