The article discusses the history and the development of primary education in the Mari region in the second half of the XIXth – early XXth centuries, which included secular and religious schools. In all types of pre-revolutionary schools catechist was the first guiding person in religious and moral education of students. It was he who taught one of the main subjects – the Law of God. This subject was very important in the framework of the Christianization of indigenous population on the territory of our region. The teaching of the Law of God had some negative moments. Catechists often showed formalism and negligence in teaching the lessons of the Law of God. However, archival documents and published materials contain a lot of evidence about the catechists that adequately performed the duty of the religious education of pupils and stood at the height of his vocation. This work examines the position of catechists and their work in the zemsky schools, which prevailed in the Mari region at the relevant time.