The article analyses the educational-didactic level of the sermons by the late 19th century priest and Lithuanian writer Juozas Tumas-Vaižgantas. The target of the sermons is the community, whose value orientation and morality must be developed. A sermon as a religious discourse enables the orator not only to comment on the Word of God revealed in the Holy Scriptures, and to explain the truths of the faith, but also, with the help of these truths, to achieve pragmatic goals: to educate, teach and provide practical knowledge. The study focuses on the category of conscience, as determining the moral decisions of an individual and having the power to influence his thoughts and feelings. The problem and the main goal of the article is to find out how this special human ability to distinguish good from evil is measured and understood by Vaižgantas himself, what role he gives it in the process of the individual’s moral education, and how his perceived conscience and its meaning correlate with the texts of the Holy Scriptures. The sermons preached by J. Tumas-Vaižgantas in Mintauja in 1894 were selected for the study. During the analysis, it became clear that for the preacher, the conscience is not only the final authority of morality, which must be obeyed unconditionally, but also that the close relationship between the conscience and faith is important. Discussing the educational role of the conscience, Vaižgantas emphasises the need to form a clear conscience.