I still don't see mythology there. Is any narrative mythological to you? If you are using the word to apply to the theory of biological evolution, for example, then you are using it much more loosely than I would. The word become interchangeable with ideas like worldview, historical account, and physical law:
"The gravitational force attracting two masses together is proportional to the product of those masses in inversely proportional to the square of the distance separating their centers"
Is that a mythological narrative in your schema of what constitutes mythology?
Standard usage of the term myth/mythos - A narrative, story or set of stories relevant to or having a significant truth or meaning for a particular culture, religion, society, or other group (despite not being objectively true).
Ideologies are myths as they are how people explain to themselves the nature of the world they live in. They just lack the aesthetic qualities of traditional 'literary' mythology.
Scientific theories are not myths although it is possible that someone could develop myths from ideas derived from scientific theories.
Somehow, you still want to credit Christianity because Christians were involved. Non sequitur. Christians do things that have nothing to do with their Christianity. Recognizing the immorality of slavery is one of them.
I believe that a Christian theologian carrying out Biblical exegesis via reasoning from specific points of scripture, and specific documenting his thought process with recourse to God and various Biblical concepts can fairly be described as 'something to do with Christianity'. This is especially true if he is presenting remarkably novel ideas that are almost unheard of in any society. This is where we disagree.
That it was dependent on an uncommon cultural 'spark' explains why it took 10,000 years to develop as an idea despite all humans being born with empathy and reason. As a sceptic, I can't believe in the silver bullet of 'rational ethics' which explains everything like magic. I find it hard to dismiss as purely 'rational ethics' a Greek theologian making arguments based on scripture that starts from a fundamentally different philosophical axiom because of this, the 'rational' Greeks couldn't even conceive a world without slavery and they had absolutely no concept of Humans being born with fundamental rights.
Why would they after all? Their mythos had no room for such concepts, as did their empiricism and scepticism. It took someone irrational to believe in something that is obviously untrue: we don't say all pigs are created equal and born with innate rights. Humans are not exceptional from any scientific perspective, we are just animals.
What is exceptional about us is our ability to create myths, stories and narratives that explain the world we live in. These myths affect all aspects of the way we interact with the world we live in for better or for worse.
These myths develop into cultures and world views which make people behave and think differently (as you see when you travel the world), and become internalised to the extent that people are not even aware of where many fundamental ideas in their society came from (and often think they are universal or simply 'common sense').
These beliefs make certain things possible and certain things impossible. For example, there is no concept of 'honour killing' in contemporary Northern European culture as they are not an honour based society. Self effacing humour in public is not really possible in societies that place a high values on 'face'.
Would you agree that culture and worldview make certain beliefs and ideologies possible, and others impossible (or at least highly unlikely)?
Do you believe that 'inside we are all pretty much the same', or that across times and cultures there is a wide diversity of ways of thinking? For example would you see the pre-modern mind as being very different to the modern one in how it sees the world?
DO you believe reason and empathy when governing human behaviour and morals depend on the myths we tell ourselves (i.e the ideologies we hold)?
The humanist method has wide appeal, and has had a civilizing effect on the rendering of scripture.
It actually has a very narrow appeal throughout history though, pretty much limited to the modern West.
Go back in time and try to explain it in most societies and it would make no sense.
"Mr Caesar sir, don't you realise you have a duty of care to the barbarians?"
"Why is that?"
"We are all part of a common Humanity and are born with inalienable rights that you shouldn't violate"
"
"
"Mr Aurelius sir, if we all work together we can solve humanity's problems through our collective reason. Our world will keep on gradually getting better and better for ever"
"Hubris is neither wise nor virtuous my dear chap, one cannot conquer fate. One must have the moral courage to live knowing the world is beyond their control and understanding. That is what it means to be a man."
My position remains: Whatever ideas you consider essential to humanism and its emergence as an ideology, Christianity was not their source, nor was it necessary that the West be Christian for humanism to have arisen there first.
You are consistently making the mistake of choosing how
you think Christianity ought to be defined and conceptualised in a normative sense, rather than looking at how specific people interpreted it in the past in a positive sense. You are also saying that because Christian A believes X, then Christian B can't believe Y.
Seeing as you are unwilling to accept a Christian theologian reasoning directly from scripture and explicitly stating his reasoning as being evidence for even a quantum of Christian influence though, it is unlikely you will consider the more subtle influences as having any impact whatsoever. I believe that culture has a big impact on ways people think though and that European culture cannot be neatly abstracted from its Christian (and Greek and Roman, etc.) influences.
Even if the influences were 'anything but Christianity', would you at least agree that: Universalism, Humanity, Progressive history & Rights that derive simply from existence are necessary for Humanism to exist and that they are not found in the vast majority of human societies throughout history?
Like I mentioned before, you can't have a concept of honour killing without an honour based society. If you are anything like me you can't even imagine how people who carry out honour killings must think and reason. I certainly can't empathise with them in any way or put myself in their shoes. Their actions are 'rational' according to their own worldview though, and can be motivated by empathy (for the family rather than the victim of course).
Would you also agree that just as honour killing makes no conceptual sense to you, many of the ideas on which Humanism is based would make no conceptual sense to people in most historical societies?