Answer
The New Testament uses the phrase child of God or children of God several times. First John 3:10 explains what it means to be a child of God: “This is how we know who the children of God are and who the children of the devil are: Anyone who does not do what is right is not God’s child, nor is anyone who does not love their brother and sister.” John is not referring here to legalists who rigidly work to earn God’s favor (Titus 3:5). He is describing the life of someone who has truly received Jesus Christ as Lord and Savior. The life of a child of God will be radically different from the life of an unbeliever. A child of God has a desire to live in a way that pleases the heavenly Father (1 Corinthians 10:31), a life characterized by love.
Many people wrongly believe that everyone is a child of God. Since human beings are created in God’s image (Genesis 1:27), aren’t we all His children? The Bible says no. Every human being is designed by God and loved by Him, but we can only become His children when we are adopted by Him (Ephesians 1:5; Romans 8:15). Because of our sin, we live under the tyranny of Satan, the god of this world (2 Corinthians 4:4). We are enslaved by sin and live to follow its dictates (John 8:34; Romans 6:16). Sin-drenched humanity cannot enter the presence of a holy God. Our sin must be forgiven and our natures restored before we can have fellowship with the One we have offended (Psalm 51:7).
Second Corinthians 5:17 describes what happens when we are born again into the family of God through faith in Jesus: “Therefore if any man be in Christ, he is a new creature: old things are passed away; behold, all things are become new” (KJV). Jesus taught that becoming children of God means we must experience the new birth (John 3:3). To be a child of God means our old sin nature is replaced with a nature that wants to please the Lord. We still sin (1 John 1:8), but we have “an advocate with the Father—Jesus Christ the righteous” (1 John 2:1). Being a child of God means our sins are paid for and our fellowship with God has been restored.
Being children of God means we have access to the “throne of grace” through prayer, any time and from any place; we have the promise that “we may receive mercy and find grace to help us in our time of need” (Hebrews 4:16). The child of God trusts his Father to supply all his needs “according to the riches of his glory in Christ Jesus” (Philippians 4:19). He is confident that the “Father in heaven [will] give good gifts to those who ask him!” (Matthew 7:11).
A child of God has an eternity in heaven guaranteed (Ephesians 1:13–14; John 3:16–18). Jesus has already paid the entry fee for every person who trusts in His death and resurrection. Children of God live in the hope of seeing Jesus face to face, and so they “purify themselves, just as he is pure” (1 John 3:3). A child of God is eager to do good works (Titus 2:14), because saving faith is a faith that changes us (James 2:14, 26).
A child of God is no longer a child of the devil and no longer plays in the devil’s backyard. God sets about transforming His children through the power of the Holy Spirit, and they begin to take on a family resemblance (Philippians 2:12–15). If we do not begin to look like our Heavenly Father in word, desire, and action, we are most likely not really His (1 John 1:5–6; 2:3–4).
Human beings were created to live as children of God. Sin marred that purpose and broke that relationship with God. Christ restores us to that original relationship as we repent of sin and place faith in Him. God calls people from every era, region, and status in life to be his children (John 6:44). For all eternity, the sons and daughters of God will worship Him as one, united as a family from “every nation, tribe, and tongue” (Revelation 7:9; 14:6). A child of God lives for Him on earth and eagerly awaits a future with Him in heaven (Philippians 1:21; Galatians 2:20).