1 tn The καί (kai) is epexegetical/explanatory (or perhaps resumptive) of the commandment(s) mentioned in the preceding verse.
2 tn This verse begins with the phrase καὶ αὕτη ἐστίν (kai {auth estin; cf. the similar phrase in 3:11 and 1:5), which is explained by the following ἵνα (Jina) clause, “that we believe in the name of his Son Jesus Christ.” The ἵνα thus introduces a clause which is (1) epexegetical (explanatory) or (2) appositional. By analogy the similar phrase in 3:11 is also followed by an epexegetical ἵνα clause and the phrase in 1:5 by an epexegetical ὅτι (Joti) clause.
3 sn The author of 1 John repeatedly attributes the commandments given to believers as given by God the Father, even though in John 13:34-35 it was Jesus who gave the commandment to love one another. 2 John 4-5 also attributes the commandment to love one another directly to the Father. Thus it is clear that God the Father is the subject of the verb gave here in 3:23.