Notice what John says here:
My little children, I am writing these things to you so that you may not sin. But if anyone does sin, we have an advocate with the Father, Jesus Christ the righteous; and he is the atoning sacrifice for our sins, and not for ours only but also for the sins of the whole world (1 John 1.1-2).
John's stated purpose is to write to his audience so that they do not sin. But what kind of language does he use to accomplish this? Does he threaten them with hell-fire, motivating them with fear? Does the threat of God's wrath motivate their righteousness, in his mind? Not at all!
Indeed, John has no trouble admitting that, even if they should sin, provisions have made for their forgiveness. During their entire lives, they have an advocate with the Father, namely Jesus Christ the righteous -- the true and only righteous one. A righteous man's prayers mean much in God's eyes; James says that the prayer of the righteous is powerful and effective (Jas 5.16). How much confidence should we have, then, knowing that Jesus Christ who alone is truly righteous intercedes for our sake with the Father? John goes so far as to say that he is the atonement for our sins; his entire life and continued existence, not merely his death, is the atonement for our sin.
John does not threaten or make use of hell-fire to motivate holiness in his listeners. He even goes so far as to say that, if they should sin, they have every reason to be confident that they will be forgiven. Now in the minds of so many people, preaching like this is dangerous and perhaps foolish. Won't people take advantage of God's goodness? Won't they understand God's willingness to forgive them as providing license for their sinfulness? Evidently John sees no problem here. His concern is not to produce fearful disciples, motivated by the terror of punishment, but rather loving disciples, who will love God and love each other, just as God himself is love. This is the whole of John's epistle in a nutshell: God is love, and Jesus taught us that we ought to love all, as well.
Consider what David Bosch says:
To evangelize is to communicate joy. It conveys a positive message; it is hope we are holding out to the world. Evangelism should never deteriorate into coaxing, much less into threat. . . . People should turn to God because they are drawn by God's love, not because they are pushed to God for fear of hell (Transforming Mission, p. 423).