The renewed interest in moral formation among theological ethicists has elicited strong critiques from those concerned with an alleged overemphasis on human agency in character development. While such concerns cannot be brushed aside lightly, the solution is to situate human agency within a larger theological frame. As John Webster suggests, theological ethics should begin talking about the self and its agency by offering a “moral ontology” that includes a “moral anthropology” of human agents within the “drama of human nature, origin, and destiny” and the moral “field” or “space” of selfhood and action. Drawing on recent studies of Johannine ethics, I argue that 1 John 3:1–3 provides a programmatic description of just such a moral ontology. I then consider the epistle’s account of imitation in light of this ontology. Drawing on a second-person Thomistic virtue ethic, I argue that, for John, imitation serves as a second-person practice of moral formation whereby believers actively seek to purify themselves as Jesus is pure (1 John 3:3). Such theological interpretation adds support to the recent recovery of Johannine ethics and suggests that such an ethic may make serious contributions to contemporary discussions of moral formation.