What's Wrong with the "No True Scotsman Fallacy"?

Imagine two British gentlemen sitting in an English garden engaging in conversation about the Queen's knights. The first makes the assertion, "All of the Queen's knights have been brave."

The second, a more circumspect individual, responds, "But what about Sir Robin? He wasn't brave at all."

"Well," responds the first, "that's because he wasn't a true knight."

What, if anything, is wrong with the response of the first British Gentlemen? Anyone familiar with the ongoing debate between Christians and Atheist/Skeptics on the Internet probably believes that the first of these two gentlemen has committed the "No True Scotsman" Fallacy. If you are unfamiliar with the fallacy, it probably means that you have not been engaging in these types of debates because it is almost never used anywhere else. There is a reason for that: it really isn't much of a fallacy. Perhaps I should say that the "No True Scotsman" Fallacy is No True Fallacy, but that would be a little harsh.

For those unfamiliar, the "No True Scotsman" Fallacy seems to be increasing in popularity over the Internet and is usually raised when a Christian claims that some bad person who has somehow claimed to be a Christian is not really a Christian, e.g., Adolph Hitler. A good, lengthy description of the "No True Scotsman" Fallacy can be found in an article by that same name on a atheist website entitled IronChariots.org. A less comprehensive but still informative version can be found on a website titled "Logically Fallacious" where the fallacy is given the following description:

Description: When a universal (“all”, “every”, etc.) claim is refuted, rather than conceding the point or meaningfully revising the claim, the claim is altered by going from universal to specific, and failing to give any objective criteria for the specificity.
Logical Form:All X are Y.
(it is clearly refuted that all X are not Y)
Then all true X are Y.
Example #1: In 2011, Christian broadcaster, Harold Camping, (once again) predicted the end of the world via Jesus, and managed to get many Christians to join his alarmist campaign.  During this time, and especially after the Armageddon date had passed,  many Christian groups publicly declared that Camping is not a “true Christian”. 

I still have all of the textbooks from the logic courses I took in college, and nowhere in any of these books do I find a description or even a reference to the "No True Scotsman" Fallacy. As I read through academic articles about logic that are available to me through my college's website, I don't see many philosophers appealing to the "No True Scotsman" Fallacy to make their case. So, where did this fallacy come from? According to an article on ExampleProblems.com, the "No True Scotsman" Fallacy was first conceived by Antony Flew in 1975 (when he was still immersed in his God-denier phase) in a book entitled, "Thinking about Thinking," however, it doesn't seem to be used abundantly since that time. This leads me to conclude that the "No True Scotsman" Fallacy has most likely been given legs over the Internet and has not been seen as particularly helpful by those who are professionally taught to logically consider thought-forms. In other words, while the "No True Scotsman" Fallacy originated with a true philosopher, it appears to have been largely adopted by Atheists/Skeptics championing the fallacy over the Internet because they can use it to make Christians look bad when they don't agree that Hitler was a Christian. You know how it goes:

Christian: Christians wouldn't kill millions of people.
Atheist: What about Hitler? He said he was Christian and was a member of the Roman Catholic Church.
Christian: Hitler wasn't a true Christian.
Atheist: Well, you've just committed the "No True Scotsman" Fallacy, which means that you have lost the argument. 

Okay, maybe the Atheist doesn't say it exactly like that, but that's the basic rub. All the Atheist/Skeptic has to do is think of some evil person who isn't like Christians claim and any effort to distinguish the evil person becomes a violation of the "No True Scotsman" Fallacy. Checkmate.

Not quite.

What's wrong with the "No True Scotsman" Fallacy? The problem is that it is a fallacy of equivocation. But it isn't simply the equivocation on the part of the person who is making the assertion that "All X are Y"; rather, it is the equivocation in the term X by both of the parties. Consider my example of the two British Gentlemen, above. Apparently, the first British gentleman is violating the "No True Scotsman" Fallacy, right? Well, he may be violating the fallacy as written, but he is not committing a logical fallacy. 

The problem in the example is that the two British gentlemen actually disagree on the definition of what constitutes one of the Queen's knights. I am certain that both of them would agree that one of the necessary factors to be a knight is to be knighted by the Queen. The second gentleman, however, probably assumes that being knighted by the Queen is the only qualification needed to be a knight. The first gentlemen apparently disagrees. He appears to believe that being knighted by the Queen is not enough to become a "true knight." Instead, he has additional qualifications to make someone a "true" knight that the second British gentlemen is not recognizing. The first British gentlemen believes that being a knight requires that the knight be brave, and it is likely the he has other characteristics in mind when he speaks of a "true knight" such as chivalry.

You see, to the first gentleman, the word "true" has meaning and isn't merely a dodge as the "No True Scotsman" Fallacy asserts. There really isn't a fallacy in the conversation -- only a clarification of terms is taking place. The first knight has additional qualifications to make a knight a "true" knight, whereas the second has only one qualification. Neither is wrong nor has either committed a fallacy -- they have just not spelled out their particular understandings of what constitutes a knight or "true knight" to each of the parties in the discussion.

With a little thought, anyone can think of thousands of examples. Suppose Thomas, a person who clubs baby seals, joins Greenpeace and pays the dues. If it is argued that all members of Greenpeace would never club a baby seal to death, but it turns out that Thomas is discovered in the Arctic clubbing baby seals to death, would the Greenpeace member be wrong in asserting that Thomas is not a true member of Greenpeace? Of course not. Thomas if violating the purpose of the organization.

Suppose that Olivia, a woman who believes that no one should be permitted to own guns, joins the NRA and pays the dues. Isn't it safe to say that I can still assert that all NRA members favor an interpretation of the Second Amendment to the Constitution that allows most people (felons and a few others excluded) to own guns even though someone can point to Olivia as being a member of the NRA who opposes the ownership of guns? I think I could confidently insist that Olivia is not a true member of the NRA. Would it make sense to contend that I was committing the "No True Scotsman" Fallacy and therefore had lost the argument if it means that Olivia should be considered representative of the NRA's positions on gun control?

Note that both of the examples include organizations that stand for something. If the only qualification needed to be a member of the group is simple membership then the "No True Scotsman" Fallacy may work. For example, if I were to say, "No graduate of Centerville High School would ever commit a crime," and you were to point out that Craig, a graduate of CHS, had committed armed robbery, my retort of "Craig isn't a true graduate of CHS" would seem to be "moving the goal posts" and fallacious. So, there is a circumstance where the "No True Scotsman" Fallacy works, but it is really quite limited. The fallacy is not as broad or robust as Atheists contend.

So, is Christianity more like being a member of Greenpeace or is it more like being a graduate of Centerville High School? Even the shallowest of investigations should result in the conclusion that it is more like being a member of Greenpeace. Christianity isn't just about joining a church or claiming to be a Christian. Rather, Christianity is a commitment of one's life to God. Jesus noted that not everyone who claims to follow him is really his disciple. ("Not everyone who says to Me, 'Lord, Lord' will enter the kingdom of heaven, but he who does the will of My Father who is in heaven will enter." ~ Matthew 7:21) The Bible says that those who are Christian will exhibit the fruits of the Spirit. ("But the fruit of the Spirit is love, joy, peace, forbearance, kindness, goodness, gentleness and self-control." ~ Galatians 5:22-23a)  1 Corinthians 5 instructs Christians to remove the wicked people who dwell among the people of God demonstrating again that not everyone who is in a church is to be automatically understood to be a Christian. (1 Corinthians 5:12-13)

This leads to the conclusion that a Christian does not commit a logical fallacy when he denies that some wicked person or another is not a true Christian. The word "true" does have meaning, after all.

Knowing that Atheists/Skeptics will continue to try to hammer Christians by applying the "No True Scotsman" Fallacy where it shouldn't be applied, how should Christians respond to this argument? I think that the better way is to be watchful for when the Atheist/Skeptic is trying to set up the fallacy and respond by asking a question about what the Atheist/Skeptic means by asking a question in response that will clarify what it means to be a Christian. An example might look like this:

Christian: No Christian would hate a homosexual.
Atheist: What about Fred Phelps? He and his church picket at funerals claiming that "God hates fags."
Christian (seeing the "No True Scotsman" Fallacy about to be inaccurately applied): So, do you think that Fred Phelps is a Christian?
Atheist: Of course he's a Christian, he's the pastor of a Baptist church.
Christian (now having a clearer understanding of what the Atheist/Skeptic believes to be the definition of Christian): That's interesting, because I think that being a Christian is more than merely being the member or even the Pastor of a Church, don't you? I mean, if you were to decide to join a church but still didn't believe in God, would you automatically be a Christian?

You see, this is a way to work around the claim that one is committing the "No True Scotsman" Fallacy. Not that the Christian would be committing the fallacy by asserting that Fred Phelps isn't a Christian, but it avoids having to convince the Atheist/Skeptic who is distracted by spiking the football that her understanding of the "No True Scotsman" Fallacy isn't accurate.

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P.S. Yes, I know that Sir Robin is a fictional character, so let's please have no one accuse me of being ignorant on that basis (I may be ignorant on another basis, and I would welcome that being pointed out, but let's not get nitpicky).