John 3:16 does refer to salvation from sin through faith in Jesus, as we usually expect. But we do not catch the full meaning of this verse unless we read the Gospel of John the whole way through. The rest of the Gospel sheds light on what this verse means about the “world” (for instance, it includes Samaritans–see 4:42 in context), on how God expressed his love (by describing the cross), and other issues. We focus here on what John 3:16 means by saving faith. Someone may say he believes in Jesus, yet this person may attend church once a year and continue to live in unrepentant sin (let us say this person murders people every other weekend). Is this person really a Christian? What does it really mean to “believe” in Jesus?
The rest of the Gospel of John clarifies what Jesus means here by saving faith. Just before the conversation in which Jesus speaks 3:16, John tells us about some inadequate believers. Many people were impressed with Jesus’ miracles and “believed” in him, but Jesus refused to put his faith in them because he knew what was really inside them (2:23-25). They had some sort of faith, but it was not saving faith.
What would happen if someone professed faith in Christ, then later renounced Christ and became a Muslim or worshiped old Yoruba gods? Would their earlier profession of faith be enough to save them in the end? The question is not hard to answer in light of the rest of John’s Gospel, though some of us may not like the answer. Later in the Gospel of John, some of Jesus’ hearers “believed” in him, but he warned them that they must continue in his word, so proving to be his disciples and learning the truth which would free them (8:30-32). By the end of the chapter, however, these hearers have already proved unfaithful: they actually want to kill Jesus (8:59). Jesus later warns that those who fail to continue in him will be cast away (15:4, 6). In John’s Gospel, genuine saving faith is the kind of faith that perseveres to the end.
The purpose of John’s Gospel was to record some of his signs for Christian readers who had never seen Jesus in person, that they might come to a deeper level of faith, the kind of faith that would be strong enough to persevere in following Jesus to the end (20:30-31). John makes this comment right after narrating the climactic confession of faith in this Gospel. Jesus summons Thomas to “believe,” and Thomas expresses his faith by calling Jesus, “My Lord and my God” (20:27-28). Jesus’ deity is an emphasis in John’s Gospel (1:1, 18; 8:58), so of all the other confessions about Jesus’ identity in this Gospel (1:29, 36, 49; 6:69), this is the climactic one: He is God. The content of Thomas’s faith is correct, but John wants more from his own readers. Correct information about Jesus is necessary, but by itself correct information is not necessarily strong faith. Thomas believed because he saw, but Jesus says that he wants greater faith that can believe even before it sees (20:29). John’s readers believe because he narrates his eyewitness testimony to them (20:30-31), confirmed by the power of the Holy Spirit (15:26-16:15).
In John 3:16, saving faith is not just praying a single prayer, then going on our way and forgetting about Jesus for the rest of our lives. Saving faith is embracing Jesus with such radical dependence on his work for us that we stake our lives on the truth of his claims.