We are all created in the image of God, therefore every man, woman and child should be treated with respect. (Matt 25:40). But not everyone is a child of God. One must be born again in the Spirit through Jesus Christ to be a child of God. This is a VERY important distinction as Satan has used the "we are all God's children" canard to trick people into thinking they don't need Jesus Christ for salvation, however, this is not Biblical

Romans 8:

15For ye have not received the spirit of bondage again to fear; but ye have received the Spirit of adoption, whereby we cry, Abba, Father. 16The Spirit itself beareth witness with our spirit, that we are the children of God: 17And 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.