The elder - See the introduction, Section 1, (2,d).
Unto the elect lady - The elect or chosen Kyria. See the introduction, Section 2. He addresses her as one chosen of God to salvation, in the use of a term often applied to Christians in the New Testament.
And her children - The word here rendered “children” (τέκνοις teknois) would include in itself both sons and daughters, but since the apostle immediately uses a masculine pronoun, τοις tois it would seem more probable that sons only were intended. At all events, the use of such a pronoun proves that some at least of her children were sons. Of their number and character we have no information, except that (the notes at 2 John 1:4) a part of them were Christians.
Whom I love in the truth - See the notes, John 3:18. The meaning here is, that he “truly” or “sincerely” loved them. The introduction of the article the here, which is not in the original, (ἐν ἀληθίᾳ en alēthia) somewhat obscures the sense, as if the meaning were that he loved them so far as they embraced the truth. The meaning however is, that he was sincerely attached to them. The word “whom” here, (οὓς hous,) embraces both the mother and her children, though the pronoun is in the masculine gender, in accordance with the usage of the Greek language. No mention is made of her husband, and it may thence be inferred that she was a widow. Had he been living, though he might not have been a Christian, it is to be presumed that some allusion would have been made to him as well as to the children, especially since there is reason to believe that only some of her children were pious. See the notes, 2 John 1:4.
And not I only, but also all they that have known the truth - That is, all those Christians who had had an opportunity of knowing them, were sincerely attached to them. It would seem, from a subsequent part of the Epistle 2 John 1:10, that this female was of a hospitable character, and was accustomed to entertain at her house the professed friends of religion, especially religious teachers, and it is probable that she was the more extensively known from this fact. The commendation of the apostle here shows that it is possible that a family shall be extensively known as one of order, peace, and religion, so that all who know it or hear of it shall regard it with interest, respect, and love.