God's Word says we are children of God as believers in Jesus Christ. Let's look at some verses to prove this:
"But as many as received him, to them gave he power to become the sons of God, even to them that believe on his name."
"For as many as are led by the Spirit of God, they are the sons of God."
"The Spirit itself beareth witness with our spirit, that we are the children of God. And if children, then heirs; heirs of God, and joint-heirs with Christ; if so be that we suffer with him, that we may be also glorified together."
"Behold, what manner of love the Father hath bestowed upon us, that we should be called the sons of God: therefore the world knoweth us not, because it knew him not."
-1 John 3:1
So you see, the Bible says those who are in Christ are the ONLY ones who are sons or children of God, NOT everybody. Some Modernist and New Age "Christian" leaders are saying that everyone is a child of God. Consider a quote from New Age heretic Robert Schuller from Crystal Cathedral, "I found myself immediately attracted to Pope John Paul II when, upon his election to the Papacy, his published speeches invariably called attention to the need for recognizing the dignity of the human being as a child of God."
That was from Schuller's book "Self-Esteem."
See my article "LOST?" on this site for another blasphemous quote he made. He teaches that self-esteem, dignity and pride are all that matters. Here is another quote from Schuller's book, "What do I mean by sin? Answer: Any human condition or act that robs God of glory by stripping one of his children of their right to divine dignity...I can offer still another answer: Sin is any act or thought that robs myself or another human being of his or her self-esteem."
"Divine dignity?" I believe Jesus told us we must deny ourselves and to be humble. Look at Matthew 16:24-25, "Then said Jesus unto his disciples, If any man will come after me, let him DENY himself, and take up his cross, and follow me. For whosoever will save his life shall lose it: and whosoever will lose his life for my sake shall find it."
When we accept Jesus as our personal Saviour we become a child of God, an heir of God. But it is ONLY for those who receive Jesus as their Saviour to become a child of God! Rejoice in this fact fellow believers that you are true children of God by Jesus Christ!