The pervasive mythology of American exceptionalism is essentially a religious doctrine positing that the US is essentially a perfect nation. Consequently, any issues arising within the system are perceived as external threats rather than inherent flaws. This mentality fuels the polarization between mainstream Republicans and Democrats, much like a religious schism. Both sides have a different interpretation of the doctrine and view each other as heretic traitors intent on destroying the nation.
Exactly, the rift is over social issues that are safe for capitalists.