I have never found a way to get to universal ethics without…

And just to be clear, this is a sincere question. I'm writing about this topic right now and would hate to be unaware of a good argument against my position.

Is metaphysics about how you want the world to be? Just because you want a universal ethics doesn't mean there is one. However, I think there is a universal ethics and it is based on the fact that people can gain more by forming bigger groups with a greater division of labor. It's wrong to enslave a neighboring group because you gain more with less risk by forming trade relations with them. However, I have seen that these considerations don't seem to matter that much in the real world (at least in the short term), so maybe it's better to be part of an in-group that exploits everyone else and there is no universal morality. Karma that works too slow doesn't punish these acts quickly enough for people to care about it. If we had a way to make Karma work faster then people would have to think about this kind of thing a lot more though.

From an evolutionary/materialist standpoint both are merely options. One option is to trade, the other is to "crush your enemies, see them driven before you and hear the lamentation of their women" (who are now your women/slaves). There is no moral imperative, it's a consideration based on what seems to be most advantageous. In my eyes that doesn't qualify as universal ethics at all. Sometimes it is vastly more advantageous to kill all those who are in your way. In fact, that's probably the most successful evolutionary strategy: protect your people, destroy the non-your-people. Nietzsche would argue that it is also the "good" thing to do, because it selects for strength and therefore serves the human race in the long term. And as long as we are exclusively talking about the material-mental world, that is absolutely true. But if we take some kind of spiritual layer into consideration, it isn't. I would argue that universal ethics exist in this spiritual layer of reality. They are a thing of the soul, while body and mind deal in mere survival and power, like any other animal.

the bigger the in-group, and the more coordinated they are, the higher chance to exert power over the out-group. religion is a social coordination technology, like markets. they are not mutually exclusive. the fact that Christianity exists is a testament to its utility, and is in some sense a refutation of Nietzsche since Christiandom emerged victorious over splintered paganism

I find it very hard to talk about religion at all because the term encompasses such different and arguably opposed things. The original meaning of the term is "union", if I'm not mistaken. Striving for union with God. Then there's religion as in a bunch of people with power trying to tell you how to live your life because they self-identify as the good and righteous. Sometimes it seems to me that organized religion has done more to turn people away from God than to bring them closer. One thing seems certain: nothing is immune from being corrupted by power.

religion is technology to get a large number of people to act in unison. the market is another

ethnicity, nationhood. coordination technology