Behold, what manner of love, &c.— The word behold, is made use of to excite new degrees of attention; and indeed is generally used in the scripture as a kind of hand, to point out what is peculiarly worthy our attention. The word ποταπος, rendered what manner, properly signifies quantity; when it denotes quality, it is some eminent sort or high degree of the kind. In either sense it will suit this place; but the latter seems preferable. The persons who in the last verse are said to have been born of God, are here called the sons or children of God. St. John was willing to make the Christians sensible of the happiness of being continued in the family of God. If the child of the poorest man upon earth was adopted by the greatest monarch, it would not be an honour, exaltation, and felicity, in any degree equal to that of being made one of the sons of God. See Hosea 1:10. Hence we are told, that when the Danish Missionaries appointed some of their Malabarian converts to translate a catechism, in which it was mentioned as the privilege of Christians to become the sons of God, one of the translators was startled at so bold a saying, as he thought it, and said, "It is too much; let me rather render it,—they shall be permitted to kiss his feet."
The two members of this argument in the latter clause of the verse are transposed; because the world knew him not, therefore it knows us not; or, the truth is first laid down, and then the reason of it assigned. True Christians are separated from the world to be holy unto the Lord; and they differ from the world in their principles, profession, and conversation: it is no wonder therefore that the world despises and hates them. See 1 John 3:13. 1 Peter 4:3-4.John 8:55; John 15:18; John 15:27; John 16:1; John 16:33.