If one is not saved is he still considered a child of God?
“For ye are all the children of God by faith in Christ Jesus.” (Galatians 3:26)
“For as many as are led by the Spirit of God, they are the sons of God. For ye have not received the spirit of bondage again to fear; but ye have received the Spirit of adoption, whereby we cry, Abba, Father. 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.” (Romans 8:14-17)
"In this the children of God are manifest, and the children of the devil: whosoever doeth not righteousness is not of God, neither he that loveth not his brother.” (1 John 3:10)
These passages would indicate that the children of God are those who obey him, have faith in him, and have received the Holy Spirit. Since we receive the Holy Spirit when we are immersed (baptized) for the forgiveness of sins (salvation) (Acts 2:38), then it must be that the children of God are those who are saved.
Many today would try to say that all people are children of God because they were created by God. That is not how the Bible characterizes children of God.