The apostle John wrote a historical narrative (the Gospel According to John), an apocalyptic vision (the Revelation of Jesus Christ), and three epistles (1 through 3 John). Each of his contributions to the New Testament had their specific function and purpose, and one should consult each piece of literature to find the internal reason for John’s writing.
But what is the purpose of 1 John? The beloved apostle answers this question in five ways:
(1) to promote fellowship among them (1 John 1:3)
(2) to produce happiness (1 John 1:4)
(3) to protect holiness (1 John 2:1)
(4) to prevent heresy (1 John 2:26)
(5) to provide hope (1 John 5:13)
How’s that for a five point sermon?