Becoming a child of God has more do to with God than us.
But as many as received Him, to them He gave the right to become children of God, even to those who believe in His name, who were born, not of blood nor of the will of the flesh nor of the will of man, but of God. (John 1:12-13)
Although we have the choice to receive God, those who receive God do not grasp on to something that they have uniquely divined. We cannot boast in receiving God. Gaining knowledge of God and becoming a child of God has more do to with God than us.
When people claim that Christians are exclusive and boast of a righteousness and holiness that is exclusive, bigoted and intolerant (to put it in modern terms), they do not understand what they are saying. God presents Himself to us, and we either receive Him or not. It is not our choice (not by the will of the flesh or of the will of man).
The righteousness does not come from us. God extends the right to us to become His children.
If by “child of God” we mean Christian, there is no such thing as a Christian who was born into it. Being a child of God is not something that passed on to us by natural birth; it is not passed down in our genes. People do not become children of God because of birth, but because of second birth.
Nor do people choose to become children of God. No one chooses to become a child of God any more than we chose to become children of our natural parents. The event of natural birth is entirely initiated by forces outside our control, and the second birth, without which no one may become a child of God, is also initiated by forces outside or our control – by God Himself.
God does the initiating, and we do the receiving. When we are born physically, we are born through the agents of our parents. When we are born again (born from above), we are born directly through the agency of the Holy Spirit, who is offered to us and who we must receive.
In this process, we are not unwilling vessels. We must receive the offer of new life, but we are not the author of it. We are not the initiators of this new life. We are entirely dependent on God who extends Himself to us.
Children of God are born not by the will of man but by God’s will. God gave His son to the world and desires that no one would be perish, but that all would have everlasting life. Everlasting life comes from God, by being born from above, and becoming children of God. This is what God offers; we only need to receive it.
When we receive what God has offered, we are changed (born again). The proof is in the change. We do not make the change; God makes the change occur within us by His spirit that we receive when we are born from above. All true children of God know this change comes from God, not from within us. The change takes place within us, but it does not originate from ourselves. The Father of this change is God, and we simply receive it and yield to it.
 “Truly, truly, I say to you, unless one is born again he cannot see the kingdom of God.” Nicodemus said to him, “How can a man be born when he is old? Can he enter a second time into his mother’s womb and be born?” Jesus answered, “Truly, truly, I say to you, unless one is born of water and the Spirit, he cannot enter the kingdom of God. That which is born of the flesh is flesh, and that which is born of the Spirit is spirit. (John 3:3-6)
 “For God so loved the world, that he gave his only Son, that whoever believes in him should not perish but have eternal life. For God did not send his Son into the world to condemn the world, but in order that the world might be saved through him. Whoever believes in him is not condemned, but whoever does not believe is condemned already, because he has not believed in the name of the only Son of God. (John 3:16-18)
 Therefore I urge you, brethren, by the mercies of God, to present your bodies a living and holy sacrifice, acceptable to God, which is your spiritual service of worship. And do not be conformed to this world, but be transformed by the renewing of your mind, so that you may [d]prove what the will of God is, that which is good and [e]acceptable and perfect.