Here's something to think about. You are what you fear.
In the political sphere, think of what you're worried about. Think of what makes you angry. All cells in your body activate when a discussion hits this topic. You believe that the opinion you hold, maybe it's even general consensus, is the only right way. Yet, there's still a (large) group of people who think otherwise. The opposition might have a different idea of what a threat is.
So, the information someone consumes determines what they fear. And that's the basis of what they believe. I think a lot of what people believe is based on opinions. Not absolute facts. Even statistics are mostly presented as opinions. When opposite sides base their beliefs mostly on opposing opinions, the truth might be somewhere in between. Thus, you are what you fear.