Or you could take a second look at your own view of what rationality consists of. My guess is that most people will rather deny rationality to other people with whom they disagree rather than acknowledge they might have good reasons to believe what they believe.
What seems clear to me is that no one individual knows nearly enough about the world and humanity itself to say in all certainty what should be done for his own satisfaction. Instead, we have strategies that allow us to make a choice nonetheless about what should be done, including doing nothing to let others sort out the situation. Obviously some people are better informed in some areas: the financial market, the geopolitical situation, the next likely epidemics or what bargains are on offer at Selfridges. And so naturally other people are not so well informed. Yet, those less well-informed people still need to have a view on what should be done, say, about the economy, the war, migrants etc. Possibly their views may turn out to be rather substandard. However, that their views should be substandard may be entirely explained by their basic lack of information, not their lack of rationality. And thus some people may be unfairly seen as irrational when they may be just uninformed. And therefore, in fact, fairly rational. Or indeed, possibly in some cases even more rational than some of those better-informed people.
Its true that lack of information can and is sometimes wrongly classified as resulting from irrational thought processes. However, it is also true and well supported by large body of empirical studies that people are highly prone to actual irrationality, reaching conclusions that are directly refuted by their own knowledge, and processing information in ways the contradict reasoned thought and are biased by emotional preferences to reach conclusions that serve some function despite being obviously false in any objective sense.
Unfortunate the study of rationality has gotten derailed sometimes by philosophers who use the term to refer to whether a belief serves any possible function for the believer rather than whether the belief specifically serves the function of optimizing objective belief accuracy by being formed via logical evaluation of evidence that relates to the probability that a given claim is valid.
The only alternative to a belief serving any possible function is that the belief is formed via totally random factors, and since that is psychologically implausible, that means it isn't possible for a belief not to be "rational" according to that former philosophical use of the term. Making that definition useless. By using the more specified definition that at least allows for the possibility of irrational beliefs, cognitive scientists have shown irrational beliefs are pervasive. While sometimes this is because being rational requires too much cognitive resources to be worth it, there are plenty of times where people put forth extra resources just to reach and defend irrational conclusions, such as making up bullshit excuses why the can discount the majority of evidence which happens to be against their belief. Also people often use what limited mental resources they have in systematically biased ways to reach emotionally preferred conclusions, such as processing only the evidence and their own knowledge that favors their preferred conclusion, which directly contradicts the rational approach within a limited resources context of considering a random and/or representative sample of the available evidence and knowledge that is relevant to the claim.
As for politics, I think the majority of the most divisive political disagreement is not due to people differing in their knowledge, but due to either one or sometimes both participants in the disagreement failing to approach the topic rationally, due to a strong emotional/ideological bias toward a particular conclusion. Pointing to their starting assumptions (such as religious ones) as evidence that are internally rational doesn't usually cut it, because those assumptions were arrived at via irrationality to begin with.