If it walks like a duck, quacks like a duck, swims like a duck, poops like a duck .......
I’m a member of a particular PCA church, but I can’t imagine from any general or specific doctrinal comments I make that you could assert that I was in the PCA church — you know because I tell you.
You could certainly figure out I’m reformed, I’m someone at least in the Sola Scriptura camp, and that I am a predestinationalist. Probably could figure out I’m a presbyterian, and not a baptist or methodist.
But I don’t know how you could figure out whether I was in the RP, PCA, EPC, or OPC. Unless we happened to talk about the specific doctrine that separates any of those two and I gave you my opinion.
So, again I ask, what is it that makes you claim he’s a member of a church, when he says he is not? BTW, this isn’t one of those “well, he has similar beliefs” things, since you aren’t talking about the “belief system” of OPC when you call it a dead church, mention how few members it has, or how corrupt it’s leadership might be. All of those things are referencing a specific, real think that people can JOIN.
So saying someone is a member means that they are actually a member, not that you find they have affinity with the beliefs.