There is good scientific evidence that political reasoning is based on innate, non-rational principles. Nevertheless, the fact that people reason so badly about politics is striking given that people are intelligent and believe strongly that it is important for their political beliefs to be true. Religion may also be innate and non-rational, but if people are rational enough to give up God-oriented religion because there is not sufficient evidence, why do they not give up ideologies as well?
When I ask this question, the responses are quite similar to what you hear when you discuss atheism with a religious person. Atheists/agnostics cannot imagine how you could act ethically, or more broadly make sense of the world, without an ideology. That is, ideology seems to give many atheists/agnostics a value system just as religion does for believers. I believe ideologies also provide people with a community of like-minded friends, as do religious beliefs, and people are loath to alienate themselves from their friends. But if your goal is to have an accurate political view of the world, what use are such ideologies and communities if they are based on beliefs one has very little reason to think are true?