It would just be a rehash of Sam Harris's argument which depends on redefining what words like "good" and "bad" mean.
At the end of the day Harris is not really talking about moral values. He is just talking about what's conducive to the flourishing of sentient life on this planet. Seen in this light, his claim that science can tell us a great deal about what contributes to human flourishing is hardly controversial. Of course, it can — just as it can tell us what is conducive to the flourishing of corn or mosquitoes or bacteria. His so-called "moral landscape" picturing the highs and lows of human flourishing is not really a moral landscape at all.
On the next to last page of his book, Harris more or less admits this. For he makes the telling admission that if people such as rapists, liars, and thieves could be just as happy as good people, then his moral landscape would no longer be a moral landscape; rather it would just be a continuum of well-being, whose peaks are occupied by good and evil people alike. What is interesting about this is that earlier in the book Harris observed that about 3 million Americans are psychopathic, that is to say, they do not care about the mental states of others. On the contrary, they enjoy inflicting pain on other people.
This implies that we can conceive of a possible world in which the continuum of human well-being is not a moral landscape. The peaks of well-being could be occupied by evil people. But this entails that in the actual world the continuum of well-being and the moral landscape are not identical either. For identity is a necessary relation. There is no possible world in which some entity A is not identical to A. So if there is any possible world in which A is not identical to B, it follows that A is not in fact identical to B. Since it's possible that human well-being and moral goodness are not identical, it follows necessarily that human well-being and moral goodness are not the same, as Harris has asserted. By granting that it's possible that the continuum of well-being is not identical to the moral landscape, Harris has rendered his view logically incoherent.
Thus, Harris has failed to solve the "value problem." He has not provided any justification or explanation of why, on atheism, objective moral values would exist at all. His so-called solution is just a semantic trick of providing an arbitrary and idiosyncratic redefinition of the words "good" and "evil" in nonmoral terms.
Read more:
Navigating Sam Harris’ The Moral Landscape | Reasonable Faith