1 John 1:4

Here "we" is probably editorial. "These things" refers to what John wrote in this epistle. Not only would his readers experience full joy, but so would John as the readers entered into and continued in intimate fellowship with God (cf. 3 John 1:4). Joy is the product of fellowship with God. When there is no joy, there is no fellowship (cf. John 15:11; John 16:24).

In summary, John wrote as an apostolic eyewitness. He identified two dangers to readers that are still prevalent in the church today. One is the assumption that Christian fellowship is possible without common belief in Christ. The other is the assumption that someone can have a relationship with God without a relationship with Jesus Christ. [Note: Marshall, p. 107-8.] John wrote this epistle so his readers might join and continue in the fellowship with God that is possible only for those who have seen God, as the apostolic eyewitnesses of the incarnate Christ had done.

"He has the heart of a pastor which cannot be completely happy so long as some of those for whom he feels responsible are not experiencing the full blessings of the gospel." [Note: Ibid., p. 105.]

These verses, rather than 1 John 5:13, constitute the comprehensive purpose statement of the epistle. There are four purpose statements in 1 John (1 John 1:3-4; 1 John 2:1; 1 John 5:13) plus 10 imperatives (1 John 2:15; 1 John 2:24; 1 John 2:27-28; 1 John 3:1; 1 John 3:7; 1 John 3:13; 1 John 4:1 [2 times]; 1 John 5:21) any of which could possibly provide John’s purpose for writing. But 1 John 1:3-4 give his most comprehensive primary and secondary purposes in writing. [Note: Yarbrough, p. 46. See also Smalley, p. 15; and Gary W. Derickson, "What Is the Message of 1 John?" Bibliotheca Sacra 150:597 (January-March 1993):89-105.]

"It is usually true that in the introduction to a book we find the key to that book. In the first four verses of this Epistle we find the key." [Note: Mitchell, p. 21. Cf. Hodges, "1 John," pp. 883-84.]