The claims of metaethical theories concerning moral reality are generally addressed within a classification centered on moral objectivism. In such classifications, subjectivism, relativism, and other non-objectivist theories are usually presented in opposition to realist value claims. Consequently, according to the prevailing approach, subjectivist, relativist, and other non-objectivist theories are regarded as anti-realist theories that are either nihilistic or that entirely deny the existence of moral values. In this study, contrary to the dominant approach, the error theory will be examined from a non-anti-realist perspective. To this end, it will first be demonstrated that certain metaethical theories are non-objectivist yet realist moral theories. In doing so, non-objectivist interpretations of moral realism will be exemplified. The research seeks to answer the following question: Is it possible to classify subjectivist and relativist moral theories as non-objectivist moral realist theories? The study aims to present an alternative way of classifying subjectivist theories based on the moral value claims of the error theory and some other metaethical theories. The qualitative research method of textual content analysis has been employed in the study. In the first section, the debate between moral realism and anti-realism is briefly discussed. In the second section, the position of John L. Mackie’s error theory among metaethical theories is examined, and a new classification is proposed. The main claims and theses intended to be demonstrated in the study are as follows: (i) the error theory and other non-objectivist theories included in the proposed classification can be coherently defended without contradicting the fundamental propositions of moral realism; (ii) this kind of approach does not entail moral nihilism or the impossibility of morality; (iii) the classification of certain theories that criticize objective morality as nihilist or anti-realist is a consequence of the classical metaethical understanding that directly identifies objectivism with realism; and (iv) in order to transcend the objectivism-centered interpretation of metaethics, it is necessary to demonstrate the realist claims of theories that defend subjective or relative values.