Behold, how great a love the Father has bestowed on us, that we should be called children of God! For this cause the world doesn't know us, because it didn't know him.
And such we are ... It is no empty title.  The believers "in Christ" are genuine children of the Father in heaven.  The word rendered "children" ("sons" in KJV) is [@tekna], that is, related to God by the new birth; and this is a closer relationship than that indicated by [@huioi] (Paul's word, stressing the analogy of adoption)."[7] While no doubt true, in a sense, such a comment should not obscure the fact that "adoption" in Paul's usage carries all of the full benefits and privileges of sons by generation, having also the advantage of illuminating the truth that sonship is all of grace.