The Catholic Epistles are those which appear to be addressed to no particular church, but were written as general guides for Christian behavior.  I John is the fourth of the Catholic Epistles.

As far back as the early church fathers, there has been discussion of the probable authorship of the three Epistles of John.  Stylistically they are similar to each other, and to the Gospel of John, but not to the Book of Revelation, which is written in a very primitive Greek.    Suggestions as to the author include the apostle – brother of James and one of the sons of Zebedee  -- and the elusive John the Elder who may have lived in Ephesus up to around 140 AD.

We looked at the extraordinary story of  the Comma Johanneum, contained in the King James version of I John 5: 7-8.  This passage, which would be the only one in scripture explicitly describing the Trinity, is found in no ancient Greek text, but found its way into the Latin Vulgate some time in the tenth century.  When Erasmus omitted it from his pioneering  publication of the Greek text, he met with many protests that he was tampering with scripture.  The story goes that he offered to replace the section if one Greek document could be produced that included the quoted passage.  Apparently one was then produced (invented?) to order.  All modern translations omit the section, as does the latest version of the Vulgate itself.

Much of I John seems occupied with current heresies – some that denied that Jesus has come in the flesh (Docetism?  Adoptionism) and the libertine heresies such as Antinomianism.  However, I John is memorable for its beautiful poetry – I John 4:16 (and for that matter I John 3:16) has a lasting impact.