What happened to the early church after the apostles had died out in the first century? Many who had opposed the apostles soon increased in number, and these charismatic personalities like Marcion and Valentinus now had the huge following to start their own "churches" and "schools" in many parts of the ancient world. This book aims to offer primary source interaction with Irenaeus, the most significant thinker in the second century, who sensed a call to equip the church with sound doctrine.