Everyone is. And everyone should expect to find others that disagree.
OK to clarify on that point a bit.
“Opinion” ranges from tastes or preferences, through views about matters that concern most people such as politics, to views grounded in technical expertise, such as scientific opinions.
You can’t really argue about the first kind of opinion. I wouldn’t say that you’re wrong to prefer one food to another or think that a particular film is good. That’s very subjective and I’d happily hear your views on music or art or cinema – I might disagree with some of them as you might disagree with mine but it doesn’t really affect much.
The problem is that sometimes we implicitly seem to take opinions of the second and even the third sort to be unarguable in the way questions of taste are. So yes, you’re entitled to say that Boris is a genius or anti-vaxxers are onto something but you can’t expect to have your opinions respected when they’re at odds with the mountain of evidence that says otherwise.
However if someone says “yes I voted for Brexit because I believed the bus slogan but now I realise it was all a bunch of lies” then that’s a bit different, that’s a previous opinion / belief that has been overruled by the evidence to say that yes, it was all a bunch of lies.
Religion isn’t an opinion, it’s a dogmatic belief system and since there’s little evidence either way to prove or disprove the existence of God (or whatever your supreme being is called), if it’s going to fall anywhere within the above three categories, it’s probably primarily in the first list as being a question of taste (mixed in with external factors such as how and where you were brought up).
