At first glance it is somewhat surprising to find that John interrupts his second presentation of the tests—righteousness, love, and truth—to deal with doubt, at least so late in the letter. But when we reflect on John’s pastoral concern for his readers and on the nature of normal Christian experience, it is not really so puzzling. To be sure, John has developed his argument concerning the basis for Christian assurance in a masterful way. But as a pastor he knows that in spite of all he has said there will still be some who feel condemned in their own eyes and who are therefore depressed by this and lack assurance. This self-condemnation can be due to a number of factors. It can be a matter of disposition; some people are just more introspective and melancholy than others. It may be a question of health; how a person feels inevitably affects how he thinks. It may be due to specific sin. It may be due to circumstances. But whatever the cause, the problem is a real one and is quite widespread. How is a believer to deal with such doubt? How can he overcome depression? John apparently recognized this problem as a real one in his time and therefore wisely interrupts his argument at this point to deal with it.
How does a Christian deal with doubt? Although there are many causes for it, there is only one answer. It is by knowledge. The Christian must simply take himself in hand and confront himself with what he knows to be true concerning God and God’s work in his life. In other words, faith (which is the opposite of doubt), being based on knowledge, must be fed by it. This is the point that John develops at the close of this third chapter.
He does it in a broad way, however, as the outline indicates. First, he deals with the “condemning heart,” John’s own term for describing the problem. In these verses he offers two ways by which we may “assure our hearts before him.” Second, he deals with the results that flow from having thus dealt with our heart: confidence of access to God and confidence that our prayers will be answered. Finally, he deals for the first time in the letter with the witness of the Holy Spirit, treating it, however, not as some additional source of confirmation but rather as expressing itself in the three tests already elaborated.
This parenthesis in his argument (3:19-24) corresponds to a parenthesis on the Church and the world (2:12-17), occurring at a similar point in his first discussion of the tests in chapter two.
The meaning of verses 19 and 20 is clear enough in a general way, but the grammar of the verses is difficult. As a result there have been many slightly differing interpretations. The causes of the difficulty are two. First, the Greek verb peithein, which occurs in the phrase “and assure our hearts before him,” has more than one meaning. The most common meaning is “to convince” or “to persuade,” in which case the verb is usually followed by a phrase containing the content or truth of which one is to be persuaded. In this case, there is indeed such a phrase. In fact, there are two of them: “for if our heart condemn us” and “God is greater than our heart.” But neither of these gives a satisfactory sense to the passage. If they are the truth of which we are to be persuaded, the passage must mean that our love of the brethren (v. 18) convinces us of the sovereign greatness of God, which is just not true. In responding to this some have suggested that the content phrase must be supplied. That is, we are to insert something like “that we are of the truth” or “that we are of God.” But the objection here is that it is surely odd to have to supply mentally the very phrase which the verb leads one to expect to be expressed clearly.