[2:8] 1 tn “In him” probably refers to Jesus Christ since the last third person pronoun in 2:6 referred to Jesus Christ and there is no indication in the context of a change in referent.
[2:8] 2 tn The clause beginning with ὅτι (Joti) is often taken as (1) epexegetical or (2) appositional to the commandment (ἐντολήν, entolhn) giving a further explanation or clarification of it. But the statement following the ὅτι is about light and darkness, and it is difficult to see how this has anything to do with the commandment, especially as the commandment is related to the “new commandment” of John 13:34 for believers to love one another. It is far more likely that (3) the ὅτι clause should be understood as causal, but this still does not answer the question of whether it offers the reason for writing the “new commandment” itself or the reason for the relative clause (“that is true in him and in you”). It probably gives the reason for the writing of the commandment, although R. E. Brown (Epistles of John [AB], 268) thinks it refers to both.
[2:8] 3 sn The reference to the darkness…passing away and the true light…already shining is an allusion to John 1:5, 1:9, and 8:12. Because the author sees the victory of light over darkness as something already begun, he is writing Jesus’ commandment to love one another to the readers as a reminder to (1) hold fast to what they have already heard (see 1 John 2:7) and (2) not be influenced by the teaching of the opponents.