Faith is one of the central concepts in the New Testament (NT) which is used as a noun (pistis) and a verb (pisteuein) in
Greek. The concept of faith occurs about 483 times in almost all the writings of the NT.
Jesus proclaims the good news as a fact, a turn of history: God's kingdom of liberation, of salvation for the people, his great intervention on behalf of the oppressed people to fulfil the great promise. But this would not take place without the summons to people to participate in it. Humankind is therefore, called to a radical change of attitudes or to find its centre of gravity in the good news preached by Jesus: to believe. This is the whole aim of Jesus, to this he oriented his signs, activities and teaching, to reveal what the Kingdom of God "at hand" is, i.e., what new attitudes, what new relationships, what new world God designs of the human family and to call people to accept them in faith, that is to commit themselves to implement this new world by a conversion and a new way of life.
Faith in St. John John is the last great theologian of faith in the NT. Or rather he is the theologian of "believing". Unlike other authors, John's Gospel does not use the noun ‘faith’ a single time, though in his epistle faith as noun occurs once (1 Jn 5:4), but uses the verb pisteuein to believe, no less than 96 times. In fact, as he himself attests, the Gospel was written, "that you may believe that Jesus is the Christ, the Son of God, and that believing you may experience life in his name" (20:31). This is precisely the work of God, which Jesus wants that we may believe in Him whom the Father has sent (6:28). Faith in John is a fundamental idea and has to do with the decision and attitude towards the revealed or God and to his message of salvation, i.e., the acceptance of Jesus as Messiah and revelation of the father. The idea of metanoia is merged into the idea of faith in John and in Paul. Both agree that charity is a consequence of faith (cf Jn 13:34; 15:12).
John speaks of believing as a life to be lived constantly and as an experience to be shared (4:42). Faith in John is a life of personal relationship with Jesus by coming to him, listening to him, receiving him, following him, remaining in him and in his word. For John it is the person of Jesus that marks the object of faith. It means accepting him as the Son of God and source of eternal life. Thus life is the ultimate object of the Christian experience and commitment. Christ as our life is the object of faith.
A linguistic analysis of faith in John facilitates our understanding of the subject. There are four ways in which John uses the verb 'to believe'. They are: 1)
To believe that e.g. Jn 20:31. He says that the gospel is written so you may believe that Jesus is the Son of God... life. In the concept of John's faith, there is an acceptance of what Jesus is. He is the Christ, 'you are the Son of God, the Holy one of Israel' (1:49) etc., all these formulas proclaim Jesus as Christ or the Son of God or certain Christological formula, which when put together make up the creed.
2)
To believe in (into): This occurs nearly 18 times in John. Hence, you believe in Jesus Christ (i.e. his identity) or in the name of Jesus Christ (refer to the one giving eternal life Jn 6:69; 11:28). In John, faith is an understanding of God, through Jesus who is the Son of God. So the incarnate Son is the centre and hence faith also involves an acceptance of the person of Jesus.
3)
To believe: Here the reference is to believers. This comes in when he talks about the totality of Christian life. (1 Jn 3:22) talks of Jesus' basic commandment to us and Jn 6:47 and 1:7, contain the essence of the Christian mystery. Thus to believe implies acknowledgement of the person of Jesus which often means a Johannine faith in the fullest sense - To be a Christian is to believe and in believing to love.
4) To believe (with dative): This stands for the openness to see, recognize and accept the signs. This involves, believe to something e.g. Scriptures, Moses (5:46), in his writing (5:47) or the works of Jesus (10:36). So the dative case designated witnessing or testimony, or the scripture, etc., are testimony, which point to Jesus who is the object of faith. These give us a rational basis for making an assent of faith, but reason is no sufficient, since personal decision is still involved.
So, we find four kinds of faith in John. The first one is a non-faith: one who refuses signs and refuses to believe in the Word. Those who accept the signs and then accept the miracles of Jesus – that he has the power to perform such miracles. But the signs are taken merely as wonder works of power done in the name of God. That is not faith; Jesus refused such faith, e.g. when the people wanted to make him king over Israel (4:5).