The diagram in the previous post brings to mind the venerable Venn diagram. Few constructs have the power to display a concept as succinctly and clearly as a Venn diagram.
In Christianity a Venn diagram that often shows up is one that reflects St. Augustine's notion of a visible and invisible church. The former is the set of professed believers, the latter is the set of actual believers.
We can extend this using some modern internet terminology. "Self-Identified Christians" and True Christians™. The little trademark symbol is used in a pejorative manner—atheists will tack it on to mock the notion that only some Christians are legitimate. It is used as a tiny symbolic form of the "No True Scotsman fallacy" charge. But I kind of like it—the symbol that is—so I'll accept it with gratitude from my atheist comrades, in the spirit in which it was not intended.
For the most part the atheist Venn diagram for Christians is:
That is, they self-righteously make no distinction between those who claim to be Christians and those who have a saving faith. Whether this is out of actual ignorance or feigned ignorance for convenience I can't say—but I suspect mostly the latter. For it allows them to say: Fred Phelps claims to be a Christian, who am I to say he is not? As far as I'm concerned he just as much a Christian as anyone else. But atheists read the bible, they know that a Christian is to be judged by his fruit—so neither we nor they are at the mercy of accepting someone's word.
Not all internet atheists are so silly. Jason Rosenhouse once gave an example that I have used many times since. He argued something along the lines of this: if someone claims I am a Christian, I believe in Jesus. And I believe in Elvis. And I believe Elvis is Jesus then it would make no sense to accept his claim of legitimate Christianity. Bravo Jason.
No, the actual Venn diagram is the same as Augustine's:
The fascinating groups are those who, on either side, fall outside the intersection. The Self-Identified Christians who are not True Christians™ come in at least two groups: the charlatans and the self-delusional. Where is Benny Hinn? My guess: in the charlatan category. Where is Fred Phelps? My guess: in the self-delusional category. Based on his fruit I judge him, as commanded, this way: that unless, someday, he is truly regenerated he'll one day hear those frightful words: I never knew you. Of course my judgment doesn't count for squat--it only means that I refuse to accept Fred Phelps as a Christian. The point is: I am supposed to judge--I am am supposed to withhold the holy from dogs.
On the other side are equally fascinating people: True Christians™ who are not Self-Identified Christians. We have reason to be hopeful that this includes dead infants and the mentally handicapped. I personally believe it also includes people who have not heard the gospel but who have been evangelized by creation. And people who have been mislead. In any event, the bottom line: it can include anyone God wants it to include.