To be a child of God means to be born again of the Spirit of God, the Holy Spirit, Jesus Christ Himself living in you, guiding you, and teaching you. You follow and obey Him ,to be a child of God.
It does not mean carrying a Bible and applying biblical principles according to your own mind; that is religion. That
is carnal. That is not following Jesus Christ. You need to be led by the Holy Spirit. If you do not have the Spirit of Christ in you and you do not follow and obey Him, then you cannot be a disciple of Jesus Christ you cannot be a child of God. Obey Jesus Christ, repent and be baptized in water and invite Jesus into your life. If you obey Jesus and seek Him with all your heart, He will come and dwell in you. He will guide you and He will teach you and you will know Him for real. If Jesus is not in you then you are not of the kingdom of God.
May Jesus bless you.