True Christians, Muslims, and Scotsmen

Christian philosopher Jeremy Pierce recently made some interesting observations about the No True Scotsman Fallacy in relation to Muslims and Christians:

So is the No True Scotsman Fallacy only a fallacy if you're using it to say someone isn't really a genuine Christian?
To be clear: there's a huge difference between IS and what most Muslims believe and practice. Nevertheless, last I checked, the core of being Muslim is (1) to believe (a) there's one God and (b) Muhammad is his prophet and (2) to practice the five pillars of Islam. Those who say the Nation of Islam isn't really Muslim are wrong, even if there are some huge differences between the Nation of Islam and the predominant beliefs and practices of Islam.
There's a good amount of diversity within Islam, and there's no reason to assume of any particular Muslim that they fit any particular manifestation of the broader religion without knowing more about them. Nevertheless, it's very clear that it's a version of Islam that motivates al Qaeda and a different version of Islam that motives IS. They are both religiously motivated, and it's clear that they are both legitimately classified as Islamic extremism. IS is severely atypical of Islam worldwide, but that doesn't make them not Muslims.
I recommend being careful of applying the No True Scotsman Fallacy label in particular cases, because it's often abused. There are ways to go back to the original core of a belief system to see who is a genuine member of the group or to look to key documents that the group produced over time to indicate who is in and who is out. There are groups that consider themselves part of Christianity but who have clearly departed from central teachings. There are people who have adopted the label but have not believed or followed the central gospel message. And it's important to recognize that there are sometimes borderline cases where it's hard to know what the right answer is (or even if there is a right answer).
But I don't see how anyone can claim that it's the No True Scotsman Fallacy to say that Hitler wasn't really Christian in any important sense. He wasn't a follower of Jesus in any serious way, and he explicitly contradicted several core teachings of Christianity. Saying he wasn't really a Christian is not an instance of the fallacy. But saying that IS isn't Muslim is simply ridiculous, by the very standards that most Muslims use to explain their big tent admissions requirements for belonging to the religion. They do fit the criteria, and anyone who says otherwise is committing the No True Scotsman Fallacy.
I want to reiterate that most Muslims think IS theology is not just wrong but offensive. Their theology of rape, for instance, is offensive to the vast majority of Muslims, and their use of that theology to recruit men who will be able to rape sex slaves at will is pretty despicable and at odds with traditional Muslim teaching about sexual morality. Nevertheless, sexual morality, political philosophy, and other issues that set apart IS from the rest of Islam are not among the three criteria for whether someone counts as Muslim. There are Christians who believe offensive things but who accept the core Christian teaching. I wouldn't say they aren't Christian.
Yes, those would be genuine instances of the fallacy. Westboro Baptist theology is within orthodoxy, and for all we know people who murder doctors or bomb churches might as well be orthodox in their theology. Any church worth its salt would engage in church discipline with such people (and probably take the side of the law against them on legal questions), but their views are within orthodoxy.

1. Let's unpack this. When we consider criteria for Muslim identity, there are basically two questions: (i) What does it take to be a true Muslim? (ii) Is a certain practice (e.g. jihad, sex slavery) consistent with Islamic theology? 

i) To be a Muslim involves observing the five pillars of Islam: The shahadah: there is no God but Allah and Muhammad is his prophet; five daily prayers; almsgiving; Ramadan fast, and a pilgrimage to Mecca. 

Notice, here, the emphasis on actions rather than belief. Even in the case of the shahadah, it's less about personally believing the shahadah than publicly professing the shahadah. 

To illustrate, when Queen Noor (née Lisa Najeeb Halaby) married the late King Hussein, a precondition was her conversion to Islam. But conversion to Islam doesn't mean the same thing as conversion in evangelical theology. It's not like she had an epiphany in which she became convinced that the Angel Gabriel dictated the Koran to Muhammad. It's not about conviction, but saying and doing the right things. Islam is a very public religion. 

This goes to the fact that Islam is based on justification by works rather than justification by faith, unlike Christian theology. 

Of course, Islam also has a detailed code of social ethics (Sharia). But in that case, I think the question of observance or nonobservance involves a distinction between good and bad Muslims rather than true and false Muslims. 

ii) The other question is whether a particular practice is consistent with Islamic theology, or even required by Islamic theology. Islam isn't simply a religion of the book (Koran). It's a religion that's defined, not only by the Koran, but authoritative tradition, viz. Hadith, schools of jurisprudence. I think it's safe to say that in venerable Islamic tradition, jihad is considered a sacred duty. Killing the infidel is permissible or even mandatory. 

2. Christian identity is more complex. By "Christian," I'm confining myself to evangelical theology. Unlike Islam, Christian identity is centered on faith. And that has different aspects:

i) Minimal orthodoxy is a necessary condition of saving faith. This involves belief in certain doctrines. 

I say "minimal" because you don't have to be a theologian to be a Christian. 

In that respect, Christian identity has a more personal orientation than Islam. Although Christian identity has a social dimension as well (e.g. the communal life of the church), even the social dimension is grounded in this individual component: personal conviction. 

So we'd say John Spong or Dale Tuggy is not a true Christian because he lacks minimal orthodox belief. They flub that preliminary test. 

ii) However, orthodox belief is a necessary rather than sufficient condition of Christian identity. There's more to saving faith than bare assent. There's trust. Trust that's rooted in the experience of saving grace. 

For evangelical theology also has a category of dead orthodoxy. A person can be a believer but not be a true believer. 

That's because Christianity, unlike Islam, has a doctrine of original sin, which, in turn, has the new birth as a corollary. To be a Christian, it is not enough to merely believe. You must be a regenerate believer. Have sanctifying grace. Have the Holy Spirit. 

As a result, evangelical theology draws a principled distinction between nominal believers and true believers. You don't have the same distinction in Islam, because you don't have the same theological underpinnings. 

By contrast, Islam has no doctrine of original sin. Indeed, every human is born Muslim.

So we might say someone doesn't seem to be a Christian, even if they are doctrinally orthodox, because something else, something crucial, is missing. 

For instance, it's not something they live for. Not their frame of reference. If they ceased believing it, that would make little appreciable difference.

Or take loss faith. That's retrospective, but with the benefit of hindsight, we'd say they had an accidental faith. Apostasy waiting to happen. They lost their faith because even when they had it, the basis of their faith was deficient. Their apostasy exposed something that was deficient all along. 

3. Let's consider some illustrations. 

i) Are members of the Westboro cult Christian? They might pass the minimal orthodoxy test. 

However, we might still have good reason to doubt their state of grace. There's a distinction between whether their overall theology is Christian, and whether they are Christian. A distinction between Christian identity in terms of doctrine and Christian identity in terms of appropriation. Has the theology been properly internalized? 

In addition, their commitment to orthodox theology appears to be nominal. Their defining characteristic is hate-mongering. 

ii) Are Confederate theologians like Thornwell and Dabney Christian? Certainly they pass the doctrinal test. And their personal piety is not in serious doubt. 

So, yes, I'd say they were true Christians, despite their defense of Southern slavery. 

iii) Ironically, their theology made it very challenging to defend the institution of slavery. Their theological commitment to monogenism meant they couldn't deny the common humanity of black Africans. But that, in turn, made it hard to justify enslaving blacks rather than whites. Why drawn the line along racial lines? That's arbitrary.

Likewise, in the Mosaic law, Hebrew slaves were term-limited. Moreover, indentured service was voluntary. And black Christians would be analogous to Hebrew slaves (or debt servants) rather than foreign slaves. 

We could say Dabney and Thornwell were Christian, but their position on slavery was unchristian.