A.T. Robertson Commentary 1 John 3:1

"Behold what manner of love the Father hath bestowed upon us, that we should be called children of God; and [such] we are. For this cause the world knoweth us not, because it knew him not." — 1 John 3:1 (ASV)

What manner of love (ποταπην αγαπην). Qualitative interrogative as in 2 Peter 3:11; Matthew 8:27. Only here in John's writings. Originally of what country or race.

Hath bestowed (δεδωκεν). Perfect active indicative of διδωμ, state of completion, "the endowment of the receiver" (Vincent).

That we should be called (ινα κληθωμεν). Sub-final use of ινα with the first aorist passive subjunctive of καλεω, to call or name, as in Mt 2:23.

Children (τεκνα). As in Joh 1:12 and with an allusion to γεγεννητα in 2:29 in an effort "to restore the waning enthusiasm of his readers, and to recall them to their first love" (Brooke).

And such we are (κα εσμεν). "And we are." A parenthetical reflection characteristic of John (κα νυν εστιν in Joh 5:25 and κα ουκ εισιν in Re 2:2; 3:9) omitted by Textus Receptus, though, in the old MSS.

Because it knew him not (οτ ουκ εγνω αυτον). Second aorist active indicative of γινωσκω, precisely the argument in Joh 15:18f.