Not All People Are Children of God

Suppose a father should have a certain number of children, and he should give to one all his favors, and consign the others to misery—should we not say that he was a very unkind and cruel father? I answer, yes. But the cases are not the same. You have not a father to deal with, but a judge. You say all men are God's children; I demand of you to prove that. I never read it in my Bible. I dare not say, "Our father which art in heaven," till I am regenerated. I cannot rejoice in the fatherhood of God towards me till I know that I am one with him, and a joint heir with Christ. I dare not claim the fatherhood of God as an unregenerated man. It is not father and child—for the child has a claim upon its father—but it is King and subject; and not even so high a relation as that, for there is a claim between subject and King.

~Spurgeon, "Divine Sovereignty"

1Jn 3:1  See how great a love the Father has bestowed on us, that we would be called children of God; and such we are. For this reason the world does not know us, because it did not know Him. 

Eph 1:4  just as He chose us in Him before the foundation of the world, that we would be holy and blameless before Him. In love 5  He predestined us to adoption as sons through Jesus Christ to Himself, according to the kind intention of His will, 6  to the praise of the glory of His grace, which He freely bestowed on us in the Beloved. 7  In Him we have redemption through His blood, the forgiveness of our trespasses, according to the riches of His grace 8  which He lavished on us. I

Rom 8:8  and those who are in the flesh cannot please God. 

Rom 8:9  However, you are not in the flesh but in the Spirit, if indeed the Spirit of God dwells in you. But if anyone does not have the Spirit of Christ, he does not belong to Him. 

Rom 8:10  If Christ is in you, though the body is dead because of sin, yet the spirit is alive because of righteousness. 

Rom 8:11  But if the Spirit of Him who raised Jesus from the dead dwells in you, He who raised Christ Jesus from the dead will also give life to your mortal bodies through His Spirit who dwells in you. 

Rom 8:13  for if you are living according to the flesh, you must die; but if by the Spirit you are putting to death the deeds of the body, you will live. 

Rom 8:14  For all who are being led by the Spirit of God, these are sons of God. 

Rom 8:15  For you have not received a spirit of slavery leading to fear again, but you have received a spirit of adoption as sons by which we cry out, "Abba! Father!" 

Rom 8:16  The Spirit Himself testifies with our spirit that we are children of God, 

Rom 8:17  and if children, heirs also, heirs of God and fellow heirs with Christ, if indeed we suffer with Him so that we may also be glorified with Him.