Indeed
My experience being born into religious conservative white america is that phrases like “I don’t believe in” or “I don’t agree with” are just the politically correct language and/or dog whistle for “I hate that shit but I need to act polite.”
I have (RCWA) family members who, in their words, “don’t believe in Halloween”. Halloween being a holiday celebrated in many countries and one that happens every year, which is all over the media, with products in nearly every store, and even shows up on most typical calendars in this country.
I think it might have to do with their Rigorous Coupled-Wave Analysis selves.

I understand that one honestly, though using the word ‘believe’ seems inappropriate.

More like “I don’t participate in Halloween”

Halloween isn’t the example I’d personally choose (I think halloween is fun!) but a lot of holidays have become altogether too corporate, to the extent people might choose to opt out, or to celebrate in their own way, or at a different time. And I understand the sentiment.