John 20:31

But these are written
. The several ends of recording what is written in this book, in proof of Christ's resurrection, are as follow: one is,

that ye might believe that Jesus is the Christ, the Son of God;
that Jesus, who was diminutively called Jesus, the son of Mary, the son of Joseph, the carpenter's son, Jesus of Nazareth, and of Galilee, was the Christ, or true Messiah; which signifies anointed, and takes in all his offices of prophet, priest, and King, to which he was anointed; and is an article of faith of the greatest importance; and is to be believed through the signs proving his resurrection, who, according to the Scriptures, was to rise again; and which, by the signs here recorded, it appears he is risen indeed, and therefore must be the true Messiah of the prophets, and also "the Son of God"; which was a known title of the Messiah among the Jews; and is not a name of office, but of nature and relation to God, and designs Christ in his divine nature, or as a divine person; and is an article of great moment, and well attested, by God, by angels, and men; and receives a further confirmation by the resurrection of Christ, who is thereby declared to be the Son of God with power; and with this view did this evangelist write the signs, proving it, herein to be found. And his other end in recording them, is,

and that believing ye might have life through his name:
believers have their spiritual and eternal life through Christ; their life of grace, of justification on him, of sanctification from him, and communion with him; the support and maintenance of their spiritual life, and all the comforts of it: and also their life of glory, or eternal life, they have through, or in his name; it lies in his person, it comes to them through him as the procuring cause of it; it is for his sake bestowed upon them, yea, it is in his hands to give it, and who does give it to all that believe: not that believing is the cause of their enjoyment of this life, or is their title to it, which is the name, person, blood, and righteousness of Christ; but faith is the way and means in which they enjoy it; and therefore these signs are written by the evangelist for the encouragement of this faith in Christ, which is of such use in the enjoyment of life, in, through, and from him. Beza's ancient copy, two of Stephens's, the Coptic, Syriac, Arabic, Persic, and Ethiopic versions read, "eternal life".