See what kind of love the Father has given unto us, that we shall be called the children of God; and so we are. The reason why the world does not know us is that it did not know him (1 John 3:1).
After a cursory reading of this verse, one might come away with the mistaken idea that every person on planet earth is a child of God. John has a specific audience in mind when he uses the word “we.” It references those who have placed their faith in Christ, i.e. Christians and who have a corresponding change in life (1 John 2:1-2). In our Kumbaya culture, we are quick to embrace the idea that we are all God’s children. John, as well as the other writers in the New Testament, show evidence to the contrary. Here are fives lines of evidence in the New Testament that show that “to be ‘born of God’ was something quite distinct from natural human procreation” (Colin Kruse, The Letters of John, 114).
- Proponents of the view that we are all the children of God by birth may point to Acts 17:28 where Paul cites “Phainomena” a poem by the Greek poet Aratus: “For we are indeed his offspring.” One might argue that since we are all God’s offspring that would allow us to conclude that we are all God’s children. However, because we are God’s offspring, i.e. His creation, He is our Creator but not by necessity our Father.
- Jesus tells the Jews in John 8:44 “you are of your father the devil.” Notice the correlation between action and relationship. They do what their father does, the same truth that John is teaching in his letter. 1 John 3:10 “By this it is evident who are the children of God, and who are the children of the devil: whoever does not practice righteousness is not of God, nor is the one who does not love his brother.” Our actions reveal our parentage.
- Paul says that we “were by nature children of wrath, like the rest of mankind” (Ephesians 2:3). Notice the past tense verb of being ‘were’. It reveals that a change took place at a point in time, following one’s physical birth. How does this status change take place? Legally. It is called justification. Romans 5:1 “Therefore, since we have been justified [counted righteous] by faith, we have peace with God through our Lord Jesus Christ.” Romans 5:9 “Since, therefore, we have now been justified by his blood, much more shall we be saved by him from the wrath of God.” Galatians 2:16 “yet we know that a person is not justified by works of the law but through faith in Jesus Christ, so we also have believed in Christ Jesus, in order to be justified by faith in Christ and not by works of the law, because by works of the law no one will be justified.” Who’s righteousness? Not ours (Romans 3:10) but God’s (Romans 1:17; 2 Corinthians 5:17-21). (cf. Genesis 15:6; Romans 4:3, 5-6, 9). So, by birth we are all children of wrath. Something had to occur to change this, namely justification.
- Paul reminds about the vital role of the Holy Spirit in sonship in Romans 8:14-16. In the same passage, he uses the significant word “adoption” (uioqesia). The word “indicates a total break w. the old family and a new family relation with all its rights, privileges, and responsibilities” (Rogers and Rogers, Exegetical Key, 330). We all understand the concept of adoption. An adopted child was not naturally born into one’s family. It is actually a precious picture of being chosen. So we’re reminded that we are adopted children into God’s family; thus we are not naturally children of God.
- The distinction between “being” and “becoming” in John 1 is significant, especially in John 1:12-13. “In the beginning was the Word [Jesus]” (John 1:1). The verb “was” in 1:1 is the verb of being eimi in Greek. God the Son always was, is, and will be; without beginning or end. John the Baptist on the other hand “was” (ginomai). This verb of being suggests a point in time when he came into being. It is the same verb of being used for creation in v. 3: “All things were made (ginomai) through him.” It is even used of the incarnation of Jesus, when the Word became (ginomai) flesh and dwelt among us! Jesus didn’t always possess a body, he received one just like you and me at His conception (though His conception was one-of-a-kind). In this way, Jesus became flesh. So noting the distinction between always being (eimi, e.g., God the Son) and becoming (ginomai, e.g., creation, John the Baptist, and the Incarnated Christ). John says this in 1:12-13: “But to all who did receive him, who believed on his name, he gave the right to become (ginomai) children of God,  who were born, not of blood, nor of the will of flesh nor of the will of man, but of God.” Thus showing that one is not a child of God by birth, but rather one must become a child of God by being born again which comes through receiving and believing in Christ.
So, who is a child of God? Anyone who is born of God, or regenerated, is a child of God (1 John 2:29; 3:9). Let’s not be carried about by the sentimental theology of our culture. Jesus told Nicodemus in John 3:3 that he must be “born again,” referring to a spiritual birth, not a physical one (Nicodemus thought Jesus meant this [John 3:4] and Jesus rebuked him for it [John 3:10]). Faith in Christ is the only way to the Father (John 14:6). It is by trusting Christ and Christ alone that we become a child of God and are adopted into God’s family. Until then, we are children of wrath. God is not our Father. He is our Judge. God has made it possible for you to become His child. If you have not, would you place your faith in Christ alone? Just as Ananias welcomed Saul, who just days before was persecuting the church, with the words “Brother Saul” (Acts 9:17), so I hope I can call you my brother or sister in the Lord and thus we can magnify the grace of God together.