on what basis do his words indicate he is speaking only of human nature and not of historical facts?
Matt 19:3 And Pharisees came to him intent on testing him, and they asked: “Is it lawful for a man to divorce his wife on every sort of grounds?” 4 In reply he said: “Have you not read that the one who created them from the beginning made them male and female 5 and said: ‘For this reason a man will leave his father and his mother and will stick to his wife, and the two will be one flesh’? 6 So that they are no longer two, but one flesh. Therefore, what God has yoked together, let no man put apart.” 7 They said to him: “Why, then, did Moses direct giving a certificate of dismissal and divorcing her?” 8 He said to them: “Out of regard for your hard-heartedness, Moses made the concession to you of divorcing your wives, but that has not been the case from the beginning. 9 I say to you that whoever divorces his wife, except on the grounds of sexual immorality, and marries another commits adultery.”
From this above passage, can you point out why you believe Jesus is speaking only in terms of human nature?
From what I bolded above. The story of Adam and Eve was part of their culture. Jesus cited it as a reference point for them and turned it back on them as they claimed the scriptures supported them. In other words, "It says in your own writings which you claim to justify you something with contradicts you". It was not a statement about Jesus' thoughts about the historicity of them. The were figures that were part of his culture's mythology which was a cornerstone of their belief systems. All cultures have these.
He was simply using them as a vehicle of communication. Functionally, this is how he was using the citation. Not to say jack diddly about earth history in the manner you wish to hear.
Neither Jesus or anyone in his culture ever thought in terms like this. This mode of thinking is Modern, post 1700's Europe. And you are entirely reading into this Modern thought in the passage, and trying to get it to say what you want it to say. Hence, it is not Jesus' interpretation you are citing, but your own.
Now to add another layer to this, even if Jesus took them as actual historical figures in the Modern sense of the word, as if he possibly even thought in terms like this which I can safely say he would not have, as he was after all a part of his culture, it has no bearing whatsoever on Modern arguments about the history of mankind. Aside from it being entirely about value systems, and not anthropological studies, the best you could say is Jesus assumed they were. And that proves nothing as well. I do not believe that Jesus, in any religious sense of the word, understood everything there was to know about everything, like knowing what the lottery ticket numbers were going to be 2000 years in the future, or the details of earth history on geologic scales, evolutionary terms, etc. Yes Virginia, Jesus would not have known this! And that doesn't matter.
Riddle me this.
Why would Jesus have to be scientifically accurate to be a valid spiritual teacher? What does being a scientist, or a geologist have to do with knowledge of timeless spiritual matters of the human condition? What on earth do you imagine omniscience means? Some sort of magical seer who sees all, knows all? That's not Jesus. That's the
Wizard of Oz.
So now you have two good reasons why and how I understand the above Bible passage, and why I find your interpretation to only work in a very limited fashion that falls apart once you move into other areas of perceptual knowledge, such as I have laid out. And I'm sure I could add a few more layers to this as well. So as I said, I interpret this differently than you, as we each are coming from different vantage points. That's how these things work for everything we read, look at, examine, and consider in life, be that with scripture or anything else. It is not a black and white world that is either your thoughts, or error. It's all vantage points.