This isn't censorship. This is VISA/MC saying "you can't pay for porn with our service" or more broadly, "you can't pay for things that we don't want to be associated with" which is their right.
FALSE, they are not blocking customers buying adult games using their system, they are focing the stores to remove the adult content unless they will block all customers that would buy very christian products too.
Would make sense if you were telling the truth and VISA would refuse your money if you are not a religious extremist but the reality is they they force their duopoly to remove LEGAL products from market places.
I do not think VISA/MC do care about freedom of speech or anything of the sort. Nor they ever claimed to do so. But we do not have to twist ourselves into pretzels to pretend this is not censorship just because censorship is ugly word.
The baker case I think was about the cake, thus having to produce "reprehensible" art. Editorial work (steam selecting what games to promote) is Sth I strongly think is their right to choose. But having a transaction run through your network? That's on the other side of the spectrum, way closer to the "no gay customer" situation. If they'd at least pretend it's because of, idk, higher card fraud rates...