27 I am writing to you. The author appears to have been concerned that some of his readers, at least, would accept the claims of the opponents as voiced in 1:6, 8, and 10. The counterclaims the author has made in 1:7, 9, and 2:1 seem intended to strengthen the readers and reassure them (among other things) that their sins are forgiven. Further assurances of their position here is in keeping with such a theme, and indeed, the topic of reassurance runs throughout the entire letter (see the purpose statement in 5:13). Finally, in such a context the warning which follows in 2:15–17 is not out of place because the author is dealing with a community that is discouraged by the controversy which has arisen within it and that is in need of exhortation.
28 The ὅτι (hoti) that follows all six occurrences of γράφω/ἔγραψα (graphō/ egrapsa) in 2:12–14 can be understood as introducing either (1) a causal clause or (2) a content clause (if content, it could be said to introduce a direct object clause or an indirect discourse clause). Many interpreters have favored a causal translation, so that in each of the six cases what follows the ὅτι gives the reason why the author is writing to the recipients. Usage in similar constructions is not decisive because only one other instance of γράφω followed by ὅτι occurs in 1 John (2:21), and that context is just as ambiguous as this one. On other occasions γράφω does tend to be followed by a noun or pronoun functioning as direct object. This might argue for the content usage here, but it could also be argued that the direct object in the six instances in these verses is understood, namely, the content of the entire letter itself. Thus the following ὅτι clause could still be causal. Grammatical considerations aside, these uses of ὅτι are more likely introducing content clauses here rather than causal clauses because such a meaning better fits the context. If the uses of ὅτι are understood as causal, it is difficult to see why the author immediately gives a warning in the section that follows about loving the world. The confidence he has expressed in his readers (if the ὅτι clauses are understood as causal) would appear to be ill-founded if he is so concerned about their relationship to the world as 2:15–17 seems to indicate. On the other hand, understanding the ὅτι clauses as content clauses fits very well the context of reassurance which runs throughout the letter.
29 “His” probably refers to Jesus Christ. Note the last reference was to Jesus in 2:8 and before that in 2:6; also the mention of sins being forgiven suggests Jesus’ work on the cross.