" I think, but I don't know, that you're wrong about masks."

Gets the response:

"I have to say I don't admire your conviction that masks don't work, the "science" behind that belief is squishy, and I find your dismissal of them problematic. This opinion plays into the hands of the anti-vaxxers. I think it's (literally) a dead wrong belief."

So you think that when I say "I think, but I don't know..." it expresses a conviction, do you? Well I'm amazed at this apparent lack of understanding of plain English. You also misuse the word "belief" and I think you know it. One more time: mask-wearing (which I think should be voluntary in almost every circumstance beyond hospitals and care homes: in no way do I oppose or dismiss that) and vaccination are separate issues. At best I'm lukewarm about the one and a hearty supporter of the other. if you see any anti-vaxxer using my opinion about masks to support their case (you never will, but hey ho), well you know what to say to them.