The genuineness of this Gospel, i.e., the fact that the apostle John was its author, is beyond all reasonable doubt. In recent times, from about 1820, many attempts have been made to impugn its genuineness, but without success.
The design of John in writing this Gospel is stated by himself (John 20:31). It was at one time supposed that he wrote for the purpose of supplying the omissions of the synoptical, i.e., of the first three, Gospels, but there is no evidence for this. "There is here no history of Jesus and his teaching after the manner of the other evangelists. But there is in historical form a representation of the Christian faith in relation to the person of Christ as its central point; and in this representation there is a picture on the one hand of the antagonism of the world to the truth revealed in him, and on the other of the spiritual blessedness of the few who yield themselves to him as the Light of life" (Reuss).
After the prologue (1:1-5), the historical part of the book begins with verse 6, and consists of two parts. The first part (1:6-ch. 12) contains the history of our Lord's public ministry from the time of his introduction to it by John the Baptist to its close. The second part (ch. 13-21) presents our Lord in the retirement of private life and in his intercourse with his immediate followers (13-17), and gives an account of his sufferings and of his appearances to the disciples after his resurrection (18-21).
The peculiarities of this Gospel are the place it gives (1) to the mystical relation of the Son to the Father, and (2) of the Redeemer to believers; (3) the announcement of the Holy Ghost as the Comforter; (4) the prominence given to love as an element in the Christian character. It was obviously addressed primarily to Christians.
It was probably written at Ephesus, which, after the destruction of Jerusalem (A.D. 70), became the centre of Christian life and activity in the East, about A.D. 90.