I think using a political philosophy or a common enemy to unite a society is more harmful than it is good, since those things will inevitably be held sacred, and it becomes impossible to think rationally about them. Religious people are able to disagree on things like economics because the things that they hold sacred are supernatural sky gods, instead of things which are of this world (Americans are an exception due to the polarization of the two-party system and the compelling force of American Civil Religion, which makes freedom, democracy, and the Constitution into sacred things), but people who hold a political ideology like Marxism or Liberalism to be sacred (Tons of people, many of them on this very website) cannot tolerate disagreement and will ignore facts that might disprove their ideology. This is manageable when it involves nothing more than a sky god, but when it involves the very basics of how society should operate, it gets bad, quickly, which is how you get thousands of dead dissenters and a permanently stagnant society. Using a common enemy is even worse since it leads to an irrational hatred of said enemy that drives people to do horrible things to eachother, with the most infamous example being the Holocaust. The Nazis also held their political ideals to be more sacred than their religious beliefs, coincidentally.