This Crossway Classic is a great devotional commentary on the Epistles of John. It has a combination of two authors, Matthew Henry and John Calvin.
Matthew Henry writes the commentary for 2nd and 3rd John and then John Calvin writes the commentary for 1st John.
Both men are well respected for their collective works on scripture. John Calvin is best known as the advocate of the Reformation movement during the 1500's in France, Austria and Germany. He wrote his Christian Institutes and then penned a set of commentaries on most of the Bible. Although he has been gone for a long time his works are still highly cherished.
This book is short and easy to read, it is more of what I would term a devotional commentary. Laymen and Clergy will both gain some good understanding of the Epistles through these short works by Calvin and Henry.
The major emphasis on the books is that of false teachers who were coming to the church and claiming that Christ was not God incarnate and that He didn't bodily resurrect. Also there was the treatment of Demetrius who was no longer accepting letters from John and using them to teach the church, instead he was pushing his own authority and not accepting that of other apostles or missionaries who came to their church.
The Epistles do a good job in a short treatment of defending the Gospel, defending the fact that Christ was both God and man and that the church needs to be very careful of false teachers. John again expresses that he was an eye witness of Christ and the message, he heard it directly, saw the miracles and touched Christ. So he knows that he was human and let also Divine.
john Calvin and Matthew Henry both approach the work from conservative Protestant roots and do a good job of giving us many insights and thoughtful consideration of the works.