His own life is literally “his soul,” but it is rendered “his life” by most modern translations. New English Bible renders “The man who loves himself is lost.” The reason for translating “life” rather than “soul” is that the rendering “soul” does not give a true reflection of the Jewish concept of the nature of man. For the Jews there was no body-soul dualism in the way that is familiar to us, and so this word refers to one’s natural life. The same word is used in 10.15, and there Good News Translation renders the Greek “I lay down my soul” I am willing to die.
The contrast between loves and hates also reflects Semitic thought. The meaning of “to hate” in such a context means that a person considers the object he “hates” as less desirable and important than the one he “loves” (See Deut 21.15; Gen 29.31,33; Matt 6.24; Luke 14.26).
Lose is the verb translated die in 3.16 and 10.28. It is used in 17.12 with the same meaning that it has here (see note at 3.16).
For the concept of eternal life see comments at 1.4 and 3.15. Will keep it for life eternal is rendered in Anchor Bible “preserves it to live eternally.”
The translation of verse 25 involves several serious problems. In the first place, a literal rendering may be quite misleading. For example, in one language the expression “loves his own life” means that the person is kind, while “hates his own life” means that he is mean and unjust. Furthermore, in many languages one cannot speak about “loving life” or “hating life,” for the term life must itself be rendered as a verb. In some instances loves his own life may be rendered “lives just for himself.” By way of contrast, hates his own life may then be rendered “but rather lives for others.” In some languages loves his own life may be expressed idiomatically as “keeps hanging onto his own life.” The contrast then may be set up as “lets go of his own life.”
Only rarely can the radical contrast between “loves” and “hates” be employed. It is always necessary to indicate that hates refers to “loving less” or “having no regard for.”
It may also be difficult in some languages to speak about “losing life.” Such an expression can be understood only in the sense of “die,” but evidently in this verse the focus is more upon the quality of life which is lost, and not upon death. Furthermore, it is important to avoid a verb meaning “lose” which would suggest an accidental loss. The loss of real life is the direct result of one’s wishing to hang onto his own way of life. It may be possible to translate the first part of verse 25 “Whoever loves only himself will lose out completely” or “Whoever loves to do only what he wants to do will end up with nothing” or “… will come to an end” or “… will finally have nothing.” To show the contrast between loves and hates, it may be better to employ a negation, for example, “Whoever doesn’t love his own life” or “Whoever doesn’t just love himself.” The difficulty with a term meaning “hate” is that it carries too many additional connotations and in some languages may even suggest suicide.
Quoted with permission from Newman, Barclay M. and Nida, Eugene A. A Handbook on the Gospel of John. (UBS Handbook Series). New York: UBS, 1980. For this and other handbooks for translators see here .