Τέκνον appears to me, as applied to Christians, to set forth the family-name towards God; νἰός the character of the standing before the world. The latter therefore is rather the term of dignity and privilege, as contrasted (see Gal. 4:6, 7) with the servant or slave under the law (the heir, in his nonage, being νἡπιος, “infant,” no better in law,) the former is the expression of the nearest relationship to God, as really born of Him. Hence it would be well uniformly to distinguish, rendering the one always “child,” and the other “son.” This is often done in the Authorized Version, but not as thoroughly as might have been. Thus, passing over cases of a more natural kind, parables, &c, in John 1:12, and John 3:1, 2, the English reader should understand not “sons,” but children. In the Authorized Version there is much confusion of the two meanings under νἰός. Nevertheless, they are kept distinct in Rom. 8 where there is an interesting example of both words rightly rendered.
Ηαῖς, again, though often used for a young person, male or female, is more vague, and is very frequently employed for a “servant,” as in Matt. 8:6, 8, 13; Luke 1:54, 69, 12:45, 15:26. It is evident, I think, that the latter is the only right rendering of Acts 3:13, 26; 4:27 30, as it clearly is of 4:25. There is admirable order in the unfolding of the testimony to the Lord in the Acts. Peter's preaching does not go beyond the Messiahship of Jesus, and hence views Him as the holy servant of God; though, of course, he well knew and believed Him to be the Son of God. Stephen goes a step father, and bears witness to Him as the exalted Son of man. Paul preached straightway Jesus in the synagogues, that He is the Son of God. If acts 8:37 be cited as marring the symmetry of this, it ought to be known that the entire verse is wanting in the Alexandrian, Vatican, and Parisian MSS., of first-rate authority, not to speak of sixty more of inferior antiquity and worth, the best copies of the Vulgate, the Coptic, the Sahidic, the Syriac (save with asterisk in Syr. Pol.), with the AEthiopia The Laudian Greek-Latin MS. (of the seventh century, according to Wetstein), and about twenty more support it, though with singular variation; also the Armenian Version, and others of no great account. I am aware that Irenseus (Contra Heer. Lib. iii.) is cited in favor of its insertion; and certainly he does give substantially the same as the Vulgate text, though perhaps in better Greek. But that little stress can be laid on this appears to me manifest, if we compare his citation of Acts 9:20, in the following section. He may have depended for both on his memory. On the whole, I cannot doubt but that the great majority of the ablest critics are right in rejecting the verse.
As to the difference between παιδίον and τεκνίον, in their spiritual application in 1 John 2, nothing can be clearer. Both have the diminutive form, as expressive of endearment; but the τεκνία, throughout, mean the entire family of God addressed, and embrace fathers, young men, and παιδια, i.e., babes, or the least ripe in experience of that family. Hence, as has been often observed, when all are meant, τεκνία is employed, as in chap. 2:1, 12, 28; 3:7, 18; 4:4; 5:21. The distinctive use of παίδια for what we may call the infants of God's family, appears only in 1 John 2:13, 18. Elsewhere the word is used generally as in John 21:5; but this or any other use of it, in no way weakens its special bearing in 1 John 2. The reader may conceive what confusion is introduced by those, like Alford, who take παιδια, no less than τεκνια, as designative of all Christians. Besides its doctrinal moment, the distinction is important critically; for, in my judgment, this is one of those cases where very strong internal evidence turns the scale of scanty external testimony in favor of γράψω for ἐγραφα, in the last clause of verse 13.