The argument boils down to what is “really” Christianity. Charlton insists the current progressive cosmology is not Christian. Everybody else say since that’s what everybody thinks it is, it must be.
I think Charlton is right but since he doesn’t explain why, I will take a crack at it.
Christianity is concerned with the issue of who will be saved and how, that is what people God will admit to his presence and who will be condemned. Up until 1500, in the area of western Europe under the authority of the Roman Catholic Church, the answer was people who were members of the Church, did good, avoided evil, and received absolution. Since the Church had the sole discretion of granting absolution, it could also offer or withhold it based on various conditions. The most infamous were the indulgences, based on cash donations. Indulgences could be offered for other things like pilgrimages, but the request for cash is what rankled people the most.
Note that the Reformation is dated to the 95 Theses of Martin Luther. Other groups broke away from the Roman Catholic Church long before- the Cathars, the Waldensians, and the Hussites, and John Wycliffe. All these people were primarily concerned with issues of corruption and spiritual purity, which only a few really serious people care about. Receiving absolution however was necessary for church membership and social standing and avoiding Hell, so it was something most people cared about.
Christianity is not a simple and straightforward belief system. It balances a variety of things, but where that balance centers is a matter of constant debate. You can derive one idea from reading and emphasizing certain places, and another from reading and emphasizing other places. Christians are obligated to both do and believe certain things. Briefly Catholic and Orthodox Christians are doers and Protestant Christians are believers. Where the lines are drawn is a matter of theological dispute that only a small number of people really understand. Most real conflict among Christians has to do with authority, that is who you are going to listen to, and not theology.
Luther didn’t like the idea that one’s acceptance by God could be determined by what one did. He thought the Catholic clergy (of which he was a member) overemphasized “works” over “faith” and had corrupt reasons for doing so. His conclusion was that salvation was obtained by faith alone and not from works or sacraments administered by the Catholic Church. Every believer was a priest.
This led to an explosion of theology and new belief systems. The important thing for our discussion is that the question of “Who is acceptable to God? Who is good?” that had been more or less settled for around 1000 years, had been opened up again. Old answer- well-behaved members of the Catholic Church in good standing. New Lutheran answer- people who had faith in Jesus Christ. New Calvinist answer- people chosen by God solely at his discretion, evidence of which would be they are well-behaved members of a Calvinist church in good standing. (Not the other way around. This is really important.)
These answers didn’t satisfy everybody though. After all, you’re just exchanging one limited group for another. Didn’t God create all people? Must they not all then have some divine spark, some divine nature, even if at some moment they aren’t showing it? The Quakers came up with the doctrine of the Inner Light, and modern Quakers take this idea to mean all people are loved by God and will be saved. The Wikipedia article indicates there is some dispute over whether this is a true original Quaker teaching but it seems to me obvious that it must be, or it would be an experience of God no different from any other Christian experience. Quakers get and the Cathars got this “Divine Spark” from the opening of the Gospel of John; but the Gospel of John as a whole is more Calvinist than anything else. Jesus makes it clear in John chapter 10 that some people belong to him, and some don’t. That is the farthest thing from universalism.
In reality this is an idea of classical philosphy; it’s found in Plato and Marcus Aurelius. The classical philosophers believed each human being, no matter their apparent intelligence or social rank, had a “divine spark” in them from their creation by the gods. But they didn’t think this meant every person was loved in the same way by the gods.
Let’s say however that we have decided because God is love, he loves everybody, condemns no one and welcomes everyone. The idea that we need to behave has been discarded; we probably don’t even need to believe, because what is that anyway? Following any set of rules is surely superfulous. Since people are saved by God’s love, as expressed in the ministry, death and resurrection of Jesus Christ, the laws set out in the Bible are no longer applicable, at least to Christians. This came quickly to be known as “antinomianism” and Luther strongly refuted it, but it is clearly and strongly implied in his theology. The apostle Paul writes in his letters that Christians are saved through a process of grace initiated by Christ, and not through their adherence to Old Testament law; he also repeatedly refutes that believers are free to do anything.
The idea that people behaving wrongly are not evil but simply misinformed and misguided again comes from classical philosophy. Both Marcus Aurelius and Boethius (the second a Christian) admonished against hating evildoers, on the basis that they were simply ignorant.
These disputes are the fodder for millions of pages of closely spaced, tightly woven arguments. What is clear though is that two ideas of modern, liberal society- that everyone is inherently good and has value and that behavior is not a matter of good or evil but simply correct education and guidance, come from disputing and questioning Christian beliefs but are not actually themselves Christian. Nonetheless, liberal Christian beliefs in general- Quakerism, Methodism, liberal Baptist, Presbyterian and Lutheran denominations, are all based on these ideas, whether they acknowledge them or not.