If someone wants something (enough to pursue it) that you think is wrong of them to pursue, the
only way you can ever argue that fact is either to correct some factual
belief they have, or to appeal to some other value they have, something
else they want, that they
already agree supersedes the other thing you deem wrong to want, and thereby correct some fallacious step of logic in their thinking, by which they overlooked that their behavior is contrary to what they actually will prefer when properly informed and soundly reasoning. Either way, you are grounding moral facts in natural facts: the natural facts of what actually exists or how things actually work, or the natural facts of what a person really wants most in life—or more precisely, what a person
would really want most, once they are reaching a conclusion about that without fallacy from only true premises. And if you attempt to argue these things,
and you are wrong—if the facts of reality
aren’t as you insist they are, if that person
doesn’t want anything you claim they do, and still wouldn’t no matter what true facts you inform them of, then there simply aren’t any grounds for your claiming they “should” want what you claim they should. And that means
you are the one who is wrong about morality.
Theists don’t like this, because it means they will pretty quickly have to start admitting they are wrong about what is and isn’t moral. They can’t have that, so they delusionally go on about our having to obey the God they invented in their own image or else we’ll have no reason to obey any moral code at all. They are lying. And we should stop taking advice from liars. We don’t need God to justify being moral. Because the way the world really works (and doesn’t), and the things we’ll want most out of life once we know what’s really available (and isn’t), fully suffice to justify and motivate a benevolent disposition in all rational persons. Moral facts then become fully discoverable natural facts—not random ideas we stumble across in our heads (as Wielenberg’s system seems to entail), and definitely not whatever our ignorant, delusional peers or ancestors have fantasized (as all modern theism entails).
Carrier (27 March 2022). "Erik Wielenberg and How Atheists Keep Missing the Point of Grounding Morality". Richard Carrier Blogs.