Lefanis, let's quit our jobs and become Fame Detectives. We are rockin' it!
Hehehe
Perhaps a combination of the two factors then? "10th member has joined the order" and something else. I am tempted to say 10,000 followers? Nice round number, pretty attainable with some effort, although only readily available to a priest- I don't have access to a religion spread off the bat... Perhaps the second factor might be being a major faith in more than 5 regions?