1. If morality is subjective (by individual or group), as atheists/materialists claim, then what any individual/group ought to do is necessarily relative to that individual/group purpose. IOW, if my purpose is to make a frozen margarita, I ought put ice in the blender. If my purpose is to make fresh peanut butter, I ought not put ice in the blender. The ought-ness of any task can only be discerned by mapping it to the purpose for which the act is committed. Under moral subjectivism, acts in themselves are just brute facts with no objective moral value; they must be mapped to the subjective purpose to determine subjective moral value (oughtness).
2. The question “Is it moral to gratuitously torture children?” implies that whomever does such an act finds it personally gratifying in some way, and we are asking a third party if the act is moral or immoral. The only possible, logically consistent answer a subjective moralist (atheist/materialist) can give is that yes, it is moral, because the moral challenge is tautologically valid in the subjective morality model. If my purpose is to gratify myself, and torturing children gratifies me, there is a 1 to 1 mapping of act to purpose- I ought do so. It is moral by definition for anyone who is gratified by the act to do so for their own gratification.
3. If the moral subjectivist says that the act is immoral “to them”, they are committing a logical error. The acts of others can only be morally evaluated according to that particular person’s subjective purpose, not according to the subjective purposes of anyone else. That is the nature of subjective commodities and relationships. Whether or not it is something a third party “ought” do for their purposes is entirely irrelevant and is treating the third party’s purposes as if they are objectively valid and binding evaluations on the acts of others.
4. Would an atheist/materialist intervene if someone else was gratuitously torturing children? If they had the power to snap their fingers and eliminate this kind of activity from the world, would they do so? I suspect the answer to both would be: yes. Note how self-described moral subjectivists would treat their own personal preferences as if they were objectively valid and binding on others.
5. Only a sociopath can truly act as if morality is subjective. “Moral subjectivism” is a intellectual smokescreen. It is a self-deception or an oughtright lie. Its proponents cannot even act or respond to questions as if moral subjectivism is true. They betray themselves as closet moral objectivists in denial, hiding from the implications of a morality they must live and act as if objective.