Verse 5 is transitional and may be taken with what follows, as preferred in this Handbook, or with what precedes, as done for instance in Greek New Testament, Revised Standard Version, and Good News Translation.

Who is it that overcomes the world but he who believes…? This sentence may have to be restructured; for example, ‘Is there any one who overcomes the world if he does not believe…?’ or in question and answer, “Who can defeat the world? Only he who believes…” (Good News Translation), or as a statement, ‘Only he who believes … can overcome the world, no one else.’ The present tense forms is and believes may best be taken as expressing a general truth.

He who believes that Jesus is the son of God in somewhat different wording repeats verse 5.1, which see.

Quoted with permission from Haas, C., de Jonge, M. and Swellengrebel, J.L. A Handbook on The First Letter of John. (UBS Handbook Series). New York: UBS, 1972. For this and other handbooks for translators see here .