The fundamental work of the Reverend Makarii, Archbishop of Khar"kov and Akhtyr, contains a detailed exposition of the Christian doctrine held by the Russian Orthodox Church. The author describes the subject of Orthodox Theology, Christian Faith as it is given in the Divine Revelation (Part I). The second part of the treatise tells about the sources of the Orthodox Theology: Holy Scripture, Holy Tradition accepted from the Apostles, Fathers of Church, and the Councils, and the Orthodox Church as the impeccable custodian and interpreter of the Doctrine. The third part analyzes the system of Orthodox Theology in its various components. Special attention is directed to the history of the Faith and of the Church, hermeneutics, Biblical archaeology, patristics, various theological disciplines such as: dogmatic theology, comparative or revealing theology, moral theology, liturgics, canon law, homiletics and ascetics as guides for the devout Christian life. This work is a quite simple and clear manual for believers, priests and other readers interested in the history of Russian culture.