Somewhat wishing I hadn't started this.
SK was clearly being mischievous (a thing which has almost never happened before) when he pretended that everyone would immediately see that Arians weren't Christians. This left an obvious opening for Sam to pretend that couldn't see any difference between the two positions. The Dawk, after all, uses Arius vs Athanasius as his main example of meaningless theological debate.
Sam, of course, plays the standard counter-gambit – since the Aristotelian terms "same substance" / "similar substance" sound obscure and strange to us, they can't signify any real disagreement; the two schools must have been arguing about nothing whatsoever; Christians are silly etc etc. If charity were really the order of the day, he might have asked whether it made any difference if you believed that Jesus was the Creator, or merely a sub-ordinate creature. But that would require us to ask "what do we mean by difference"? That chap who did the History of Christianity on the Beeb a couple of years back pointed out that Arian art depicted a realistic, human Jesus who appears to age during his ministry, where Byzantine art of the same period depicts a more distanced, obviously divine figure. But that's a bit of a rarefied distinction. I am quite sure that Sam would be able to quite easily spot an Arian by its behaviour. It would be the one wearing a headscarf, knocking on his front door, and asking him to buy a copy of the Watchtower. Is that the kind of difference we are looking for?
We are of course, not permitted to say that "Well, the positions are different because the people who believe in the two positions believe that they are different" because Sam could then play his "Popular Front of Judea vs Judean Popular Front" card.
In all seriousness. Christians seem able to disagree with each other about quite big theological questions, and still regard each other as "fellow-Christians", albeit "fellow-Christians who should jolly well stop denying the miracle of the mass / worshipping a biscuit and come back to the true church". But Christians have found that the question of the Trinity is one about which they are unable to agree to differ. It's not a question of poor hard done by Arians saying "But we are Christians, the same as you: please let us back into your church." Trinitarians think that Arians aren't Christians; Arians think that they are the only Christians. They knock on my door early on Saturday mornings and try to convert me, which the Bishop of Rome, to give him his due, has never done.
I don't think that the question about whether the Holy Spirit proceeeds from the Father and the Son or from the Father alone is a question about nothing; I think I could have a stab at saying what the difference is and why it seemed to be important. But the Pope in Rome regards the Patriarch in ... wherever he lives, do you know, I honestly don't know... not merely as a fellow Christian, but as a fellow Christian who is so near to being a Catholic as practically makes no difference. Even though he's quite sure that he's wrong about filoque.
So why do questions like Arianism not admit of the same kind of compromise?
I understand that from a position outside of any Church, this might look odd; could Sam accept that from a position inside the Church, it seems obvious. (Obvious that Jehovah's Witnesses and Mormon's aren't Christians, but that Anglicans are simply fellow Christians who've got it badly wrong about infant baptism.) Could he perhaps accept on trust that the person of Christ is what Christianity is about; in fact what Christianity is (in the way that the Koran is what Islam is) and that while there can be very great differences of opinion about baptism, Eucharist and even ethics, you can't mess around with our understanding of who Christ is without changing – or in fact obliterating – our faith.
To press the analogy in a possibly ignorant direction; I don't think that there has ever been a textually liberal form of Islam – the Koran is either the actual word of God, or it is nothing, and without the Koran there is no Muslim religion. Would orthodox Jews say the same thing about the Torah – that you can't be "a Jew who doesn't follow the Law" because following the Law is what being a Jew means? But I may be wrong about that.
There are certainly clergy who take the view that Jesus was a teacher of ethics; that he preached a radical, revolutionary message; that his death was a political martyrdom; and that the resurrection is to be understood simply in terms of "his followers kept following his political message even after he died." Does Sam genuinely not see that this is different from the mainstream position that god came down from heaven, died on the cross to enable human beings to go to heaven, came back to life after he had been killed, and then went back to heaven? Does he genuinely not see why I, coming from the second perspective, would not be prepared to call the first one "Christian"?
Is the point "I don't think Giles Fraser really takes the liberal – modernist position that your ascribe to him."? (I am perfectly happy to concede that I may have misjudged him.)
Is the point "It doesn't matter if Giles Fraser takes the liberal - modernist position, because the liberal – modernist position is in fact indistinguishable form the traditional – conservative position." (In which case Fraser is equally to blame, since he appears to deny that Catholics and Evangelicals are Christians in any meaningful sense.)
Or is the point "It couldn't possibly make any difference whether Fraser is a liberal – modernist or a traditional – conservative because all religious positions are equally meaningless? "
I think that Sam, being what C.S Lewis called a naturalist, may find it genuinely difficult to believe that Christians are what C.S Lewis called supernaturalists. I think that he finds the idea that there is Something Else apart from the scientifically observable universe so strange that he thinks that whenever Christians seem to be talking about something supernatural, they must really be talking about something natural. "I know you say that you say that you think that Jesus died so you could get in touch with God, but you can't really mean that: you must really mean 'so that you can form a more just society' or 'so you can overcome your psychological hangups' ".
I don't think that any good Christian has ever quite believed in the parody of the Atonement which Richard Dawkins and Giles Fraser abominate. This is sometimes called "Penal Substitution": I prefer to call it the Tom Sawyer theory. (God wants to whip Becky Thatcher; but Tom Sawyer, who is innocent, volunteers to get whipped instead, so Becky Thatcher gets off scot free.) As committed a death-cultist as John Stott points out that it doesn't work because it's not fully Trinitarian: God is in fact both the one doing the punishing and the one getting punished. Mr C.S Lewis starts out his chapter on the Atonement by saying that before he was a Christian, he thought that the whipping boy theory was the one he had to believe, and that it made no sense to him. He said that once he became a Christian, even the theory of one person getting punished on someone else's behalf seemed less immoral than it had; and if you changed it to "paying a debt" or "standing the racket" then it made more sense; because it's a matter of common experience that one one person has got himself in trouble, it's the innocent person who isn't in trouble who has to get him out of it. He then propounds a rather complicated theory, based on Anselm, about human beings needing to "go back" to God, but not being able to, and Jesus doing the "going back" on our behalf.
Again: I don't quite know whether Sam really doesn't see the difference between an objective Atonement ("The death of God actually changed the relationship that the material universe has to the supernatural realm") and a subjective Atonement ("Jesus' death was a good example of not striking back against evil, however horrible it is") or whether he's pretending not to for tactical reasons. Or if I'm failing to explain it very well, which is most likely.
If the Tom Sawyer analogy is a poor one, why do people carry on using it? Because it is a very vivid and dramatic way of picturing the idea that Jesus' death made a difference. God was cross with us; Jesus was punished; now God isn't cross with us any more. Darnay was going to be beheaded; Carton switched places with him; Darnay lived happily ever after. There are other versions: the human race owed God a debt; Jesus paid the debt; now the human race doesn't owe God a debt any more. Many nasty imperialist evangelical tracts ask us to imagine a judge, or more probably a Judge, who imposes a fine on a certain prisoner and then pays it himself. We were too dirty and filthy to go to heaven; we washed ourselves in the blood of Jesus; now we are clean. Jesus went down into hell, fought with the devil and smashed down the gates, so no-one has to stay in hell unless they want to. For the first thousand years of Christian history, the most popular theory involved God playing a trick on the devil to make him exceed his authority, and idea that would be incredibly alien to almost all Christians, but important if you are are going to make sense out of the Lion, the Witch, and the Wardrobe.
The Bible talks about the death of Jesus in terms of "sacrifice". It is absolutely true that the idea of sacrifice is strange to us. But the idea was clearly not strange to the people who wrote the Bible. Jesus is the lamb of God who takes away the sin of the world; he is handed over to be executed preparation day ("when the passover must be killed"); he initiates a sort of holy role-play in which passover wine becomes "my blood of the New Covenant". Church of England churches still have a table at the front which they call an "alter"; Giles Fraser has to perform a rite involving phrases like "in memory of thy perfect sacrifice made once for all upon the Cross" and "Hallelujah! Christ our Passover is sacrificed for us." It is very reasonable indeed for a clergyman to say "We need to find ways of explicating this strange language; we need to be pretty sure we understand what "sacrifice" meant to a good Jew, and, come to that, to a pagan convert at the time of Jesus." But I don't think you can say that the whole idea of sacrifice is abhorrent, and actually anti-Christian. You can only say that if you think that the people who we depend on for our knowledge of Jesus (Matthew, Mark, Luke and John) had utterly and completely missed the whole point of every word he had ever said. Possibly you may think that Jesus was all right but the disciples were thick and ordinary, that their twisting it has ruined it for you. Once you've said that, there isn't really anything left called "Christianity" to talk about.
In Fraser's version, Christianity went off the rails pretty darn early. St Mark pretty definitely has a story about Jesus miraculously stopping a storm. Fraser thinks that miracles of the storm-stopping kind are completely contrary to the whole idea of Christianity. That's sort of a bit of a problem.
It may be that I misread Fraser. It may be that (like me and St Mark) he thinks that the point of the story of Jesus calming a storm is the final line, where the disciples say "Hang on...only Yahweh is meant to be able to tell the weather off. But that means....."; that he's saying "The point of the story is that Jesus really was Yahweh; the point of the story is not that we don't need to listen to the shipping forecast before going on boat trips from now on." It would have been nicer if he could have framed in as an affirmation of what he does believe, and not as a rant about how horrible we evangelicals are.
I'm not talking here about whether we think miracle are even possible, or whether we ought to interpret miracle stories literally or metaphorically. I am quite happy to debate with the fellow who thinks that Mark 4: 35-41 is not a news report, but (say) a commentary on the book of Jonah. But when someone says "Mark completely missed the point of what Jesus was on about; but fortunately, I get the point perfectly well" then I smile patronisingly and walk away.