I have been struggling with concept of "children of God." I understand we are made children of God when we becoming Christians, yet we are bond servants to God and Christ -- we are servants. I was wondering when it refers to us being children of God, is it a general reference like the one in Job when it refers to angels as being sons of God? He made them like He did Adam, so in a sense they're sons of God because He is their maker. Yet Christ is in a different way a Son of God. What I see in Scripture is that we are indebted to Christ in a way or a servant bought with a price, yet we are called children of God, while our calling or duty is to serve God. Luke 17:7-10 is where i was looking when this popped into my head, but it is also in Paul's writing, of course.
The phrase "children of God" is a reference to believers or Christians. "But as many as received Him, to them He gave the right to become children of God, to those who believe in His name" (John 1:12). They are contrasted as a group to Satan's followers. "In this the children of God and the children of the devil are manifest: Whoever does not practice righteousness is not of God, nor is he who does not love his brother" (I John 3:10). Or sometimes contrasted to people living by this world's standards. "That is, those who are the children of the flesh, these are not the children of God; but the children of the promise are counted as the seed" (Romans 9:8). The phrase is not used in a generic sense to say we are created by God.
Probably the most detailed passage on this topic is in Galatians.
"For you are all sons of God through faith in Christ Jesus. For as many of you as were baptized into Christ have put on Christ. There is neither Jew nor Greek, there is neither slave nor free, there is neither male nor female; for you are all one in Christ Jesus. And if you are Christ's, then you are Abraham's seed, and heirs according to the promise. Now I say that the heir, as long as he is a child, does not differ at all from a slave, though he is master of all, but is under guardians and stewards until the time appointed by the father. Even so we, when we were children, were in bondage under the elements of the world. But when the fullness of the time had come, God sent forth His Son, born of a woman, born under the law, to redeem those who were under the law, that we might receive the adoption as sons. And because you are sons, God has sent forth the Spirit of His Son into your hearts, crying out, "Abba, Father!" Therefore you are no longer a slave but a son, and if a son, then an heir of God through Christ" (Galatians 3:26-4:7).
The concept of being adopted in as a child of God is to emphasize the promised reward or inheritance that awaits us in heaven.
But our relationship with God is a complex one. A single phrase doesn't capture all aspects of our relationship. We are also called slaves to emphasize that we owe God loyalty and obedience. "So likewise you, when you have done all those things which you are commanded, say, 'We are unprofitable servants. We have done what was our duty to do" (Luke 17:10).
The key between these two ideas is the concept of redemption. I wrote an article on this a while back. "The Living Redeemer" explains how we put ourselves into slavery to sin in a manner much like the one used to pay off a debt. A family member, in this case Jesus, pays off the debt to redeem us. We remain heirs because we are family, but we are also slaves to one who rescued us because he bought us. "But God be thanked that though you were slaves of sin, yet you obeyed from the heart that form of doctrine to which you were delivered. And having been set free from sin, you became slaves of righteousness" (Romans 6:17-18).