> I mean, the rights of individuals in the US is legally guaranteed because of belief in God, and the nation still stands under God.
This country was founded on the principle of separation of church and state. It's not a Christian country. It's a country that happens to have Christians living in it.
> 74 million people voted in 2020 for a loudly Christian president and vice president.
Actually, 155 million people voted for a Christian president and VP. It's just that the Christian that got 81 million votes has a largely opposite take on this question.
> As for secular morality preachers, I didn't know they exist.
Literally anyone who gives moral advice without couching it in religion would qualify. Secular humanism enjoys some popularity.
> I wonder how they deal with moral standards if they're not set in stone, as they're believed to be in the Bible.
I don't think you have a good grasp on morality. Or on religion.
Nothing about the interpretation of the Bible is set in stone. It is interpreted this way and that to suit the the zeitgeist, or the personal interests of the chap behind the pulpit (or his friends).
Twenty different people look at it, and come up with completely contradictory conclusions about completely basic, fundamental things. And the vision that wins out is often the one with more guns and spearpoints and dollars behind it.
> Tomorrow killing Jews might become the moral thing to do.
Tomorrow?
Why not look at yesterday? Christian persecution of Jews is a millenia-old on-and-off tradition, which is a little difficult to reconcile with the so-called involatile morality. As would the heavily-Christian South, that only a century and a half ago fought a civil war with the heavily-Christian North over the right to enslave black people.
When the exact same founding documents produce such radically different conclusions, I think it's pretty clear that religious morality is about as involatile and set in stone as quicksand.