During Augustine’s early years in ministry, he promoted the idea of using the pen rather than the sword when it comes to converting those who were not Christians. However, during the Donatist Controversy. Augustine advocated the use of violence to convince the Donatists to return to the Catholic fold. This dissertation argues that disgust played a crucial role in Augustine’s change of heart. Emotions play a huge part in an individual’s decision-making process. Studies on disgust discuss its role in interpersonal conflict and in religious violence. The dehumanizing language present in Augustine's letters when he describes the Donatists helps create an atmosphere where disgust's strong presence can be felt. The question of purity became an important question since both groups argued that they were the “true, pure Church.” Both groups traced their spiritual lineage to Cyprian as proof that they belonged to the true African Church. By examining Augustine's Letters, one can see the shift in tone and characterization of the Donatists by Augustine. Over the years, the disgust felt by Augustine led to a shift in his attitude, leading him to sanction the use of violence against the Donatists. Initially, the role of disgust was to prevent humans from coming into contact with harmful pathogens. As a result, humans developed a strong revulsion against harmful substances in order to protect themselves from harm. While disgust has this physical component, it also has a sociomoral component where it manifests itself against disgusting stimulus. Within this schema, anything that it deems as a moral transgression, especially as it involves question of purity, is considered as a stimulus to be avoided and rejected strongly and vehemently. While it poses no problem for a human to avoid what it deems as a disgusting stimulus such as a cockroach, it does pose a problem when another human being is seen and labelled as a cockroach. Disgust has the power to “other” human beings and creates a very strong us-vs-them mentality. Once this us-vs-them mentality is enforced, it is only natural to label another group as a "cockroach” and kill them as such. In examining Augustine's relationship with the Donatists, it is important to acknowledge disgust’s role in this particular theological and historical event. This dissertation will conclude with a contemporary application of disgust in modern theological controversies, especially as it relates to homosexuality and the role of women in leadership. Disgust’s ability to elicit such a strong and violent response in humans is a reminder of the strength of emotions to govern our actions. / Thesis / Doctor of Philosophy (PhD)