In this context, “Catholic” has no denominational meaning; the Greek word katholikós means:
“general,” “universal,” or “comprehensive.”
The catholic letters are so named because they generally do not specify a particular congregation or individual as the recipient, but are addressed to the entire Christian body.
They were first referred to as katholikós by Eusebius of Caesarea in his Church History around 300 AD. He intended to convey that these letters are addressed to the entire Christian community.
The letters cover the challenges of the early Christian church, protection against false teachings, the true content of the faith as found in the Gospels, and the manner of life expected of Christ’s followers in all areas—such as family, work, the environment, and the church.
The collection consists of written by Peter, John, James, and Jude.
The Letter to the Hebrews is sometimes counted as the eighth – or as the first of the catholic letters – because its author is uncertain; others include it among Paul’s letters.
