@mcfate It's an iffy question -- every congregation has people who came in once or twice, maybe even got their names on the address list, but never formally joined; people who attend every Sunday service but never formally join; people who joined but haven't been seen or heard from in years. And then there's the Zoom/YouTube contingent....
I'm guessing 100-500, but with many caveats.
And for the record, I'm more of a hard agnostic: not asserting anything about what I think is unknowable.