Whoever accepts is actually a participial phrase in Greek (literally “the one having”). On this construction see 12.44. The indefinite relative clause may be treated as a conditional clause, for example, “if anyone accepts my commandments.”
Accepts is literally “has.” Some commentators understand obeys (literally “keeps”) as a step beyond accepting, but this interpretation is doubtful. It is better to take the two verbs as a kind of parallelism, as in New American Bible “He who obeys the commandments he has from me is the man who loves me.” New English Bible renders “The man who has received my commands and obeys them….” It is very difficult in some languages to make a distinction between “accepting” and “obeying” commandments. Some translators try to render accepts my commandments as equivalent to “acknowledges my commandments” or “recognizes my commandments,” as if there were two stages involved in a person’s relation to the commandments of Jesus. This interpretation, however, does not carry the meaning of this passage; therefore it may be better to translate “whoever obeys my commandments” or “whoever does what I have commanded him to do.”
My Father will love whoever loves me is literally “the one who loves me will be loved by my Father.” Good News Translation inverts the order of the Greek, changing the passive into an active construction, and making my Father, the agent of the passive verb, into the subject of the active verb. Just as the first clause of verse 21 may be treated as conditional, whoever loves me may also be treated as conditional, for example, “if anyone loves me, my Father will love him.”
The verb translated reveal is used in John’s Gospel only here and in the following verse. As in the Septuagint of Exodus 33.13 it is used of a special divine manifestation. I … will … reveal myself to him is more than merely “showing him who I am.” An equivalent in some languages is “I will come to him” or “… come to him personally.”
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 .