The Shepherd of Hermas was written during the 2nd or 3rd century and contains teaching that is orthodox, not heretical. Some early church fathers—for example, Irenaeus—even considered the Shepherd of Hermas to be canonical. However, this book is not part of the biblical canon that we have today.
We do not know who wrote the Shepherd of Hermas; it does not contain any reference to its author. Several ancient sources say that it was written by Hermas, the brother of Pius I, who was the bishop of Rome from AD 140–155.
The Shepherd of Hermas is a story, where the speaker speaks about his life and growth as a Christian who was freed from slavery. The general tone of the book is that the speaker simply wants to live out the Christian life faithfully and with devotion.
The book primarily deals with ethics and living as a Christian, and is not primarily theological. The book contains three sections:
The speaker’s name is Hermas, and Hermas was a slave who belonged to a woman named Rhoda. Rhoda eventually frees Hermas. After this, Hermas has a vision concerning Rhoda, who believed that he had impure thoughts. In this vision, an old woman tells Hermas to repent and to help his people through living a devoted life.
Later, Hermas has another vision, in which an angel of repentance appears as a shepherd and gives him a number of commands. These commands became foundational to early Christian ethics.
The books that are considered canonical and part of the Bible are regarded as “self-authenticating.” The Shepherd of Hermas was likely not considered canonical because it was not written by an apostle or something directly connected to an apostle. It has a later date than other books that became part of the biblical canon.
At the same time, early Christians found value in the book, so much so that some listed the book as canonical. However, the final verdict was that the Shepherd of Hermas is not indeed a canonical book.
Below are links to the text of the Shepherd of Hermas. There are two translations.