Moral subjectivism is commonly associated with out-of-favour theories like, e.g., Alfred Ayer’s emotivism or John Mackie’s error theory. This paper approaches the field against the background of the attitudinal character of morality and religion. The possibility of a brand of moral subjectivism is established which is common to Ayer’s and Mackie’s theories in name only but seems to have considerable merits. The perspective from action theory and the philosophy of mind suggests that the problem of moral obligation, central to moral philosophy, is more convincingly dealt with by subjectivism than by its rivals: In contrast to realism or even relativism (with which subjectivism often gets confused), subjectivism can help to explain the peculiarities of obligation without forcing us to disregard the parallel problem in the field of religion. This finding calls into question the rationale for, as well as the success of, central assumptions in ontology and semantics which the realist so freely hands out in order to make his point: If religious facts and the truth-aptness of religious judgements will not explain religious obligation, moral facts and the truth-aptness of moral judgements will not help the moral realist either. So, unless we do not wish to simply cast the problem of moral obligation aside, in future, moral subjectivism must be seriously considered as a worthwhile position in its own right.