"On the Apostolic Preaching" (Popular Patristics) by St. Irenaeus of Lyons is a significant work that offers a clear and concise summary of Christian doctrine as taught by the apostles. Written for the instruction of new believers, this treatise emphasizes the fulfillment of Old Testament prophecies in the life and mission of Jesus Christ. St. Irenaeus provides a systematic presentation of key theological concepts, including the Trinity, the incarnation, and salvation through Christ. This edition, part of the Popular Patristics series, makes an essential early Christian text accessible to modern readers, highlighting the continuity and coherence of apostolic preaching.