Yeah, of course they do. They literally form the cornerstone of your worldview. If you change someone's beliefs, you change how they see the world. That sounds pretty damn big and important.

I think it's weird that people even have beliefs. Belief is a dirty word to me.

I always liked the line in Dogma about them, don't turn ideas into beliefs, you can change ideas easier than beliefs. Paraphrased and I understand how much it waters down the whole problem but I still thought the idea of it was nice. Listen and be open, you shouldn't always need to be rigid. Though mean there are still ideals I'm rigid about, respect, compassion and such. Though I always thought the idea was you thought about what worked best for everyone not just what people said you should do cause tradition.

I believe in science. I believe in justice, equality, and freedom. I believe fascism and capitalism is detrimental to humanity.

I do not believe in ghosts. I do not believe in gods, angels or demons. I don't believe in an afterlife. And I don't believe corporations are people.

Judging by all the vaguely hostile comments, you seem to have struck a chord here.

They do indeed.

My parents are deeply religious, but have never figured out that it's my siblings and I who actually answer their prayers.

Beliefs are important, beliefs are what gets us through life somewhat mentally sane.

Beliefs are (for example) the cornerstone of relationships, because you have to believe that your partner really loves you. There is no hard evidence for that so it can never be a fact, only a belief.

I believe that my neighbors don't plan to kill me in my sleep (why should they, I am a nice and easy neighbor), I believe that the person at the fast food corner doesn't spit on my food (and that they had washed hands after using the toilet), I believe that my landlord will some day repair the water damage in my second bathroom (and put all the bathroom stuff like sink, shower and toilet back in).

One could say that belief is behind everything where "trust" is involved. Belief is just accepting something as true, either because it is something that is a concept without hard facts (love, religion, justice, freedom, money, "the good in people") or it is something where the information are lacking either because they are not fully known yet or because it is such a complex topic that having all information is (nearly) impossible.

I believe for example that climate change is real, because I trust (there it is again) the science. I have to believe in this case because I can't have all the information without studying climate sciences, and one can argument that even our best climate scientists doesn't have all the information (models are still incomplete and simulations don't use all possible parameters) so even they have to believe for some parts.

Beliefs become problematic when people take them as hard facts, as dogmas, and become extreme.

I believe that taking extreme positions is always wrong and a way to disaster and suffering. That's one reason why I don't like faith and are against cults of any kinds.

Because as Terry Pratchett astutely notes in the Hogfather belief is what makes the human society possible. We invented justice, mercy, duty, laws, money etc. They exist only because we believe in them. Some beliefs make the world better, other ones worse, and we should try to emphasize the former and minimize the latter.

The more I think about it, the more I realise how less I understand this word.

Yes and I believe this isn't really a showerthought

Read the book Sapiens.

Being able to believe in fiction is what allows humanity to function.

The difference between a belief and a theory is no one was ever burned at the stake disagreeing about a theory.

Belief is a tool for achieving effects; it is not an end in itself. -Peter J. Carroll

Belief isn't inherently bad you can believe in observational facts. It's faith that's dangerous. Any system that requires you to maintain beliefs without observable facts or in the face of negative confirmational facts is a problem.

I believe I'd like another drink.

All I know is that nobody knows shit.

Beliefs lead to actions. Actions affect others. It's not super complicated.

Because everything we can say about reality is through the human perspective and the construct of language. We believe that this can yield us truths. But its just a belief. Our human-ness might just as well blind us to what is actually true. And as such, most of everything we think we know is based on belief. There is no escaping this problem.