FAQ:I know that as Christians we are “born again of incorruptible seed” (1 Pet. 1:23). Why then do several places in the Church Epistles speak of our being “adopted” by God?
The Greek word translated “adoption” is huiothesia, and it occurs only five times in the New Testament, all in the Church Epistles (Rom. 8:15, 23; 9:4; Gal. 4:5; Eph. 1:5). According to Vine's Lexicon it means: “the place and condition of a son given to one to whom it does not naturally belong.” Louw and Nida’s Greek Lexicon says: “to formally and legally declare that someone who is not one’s own child is henceforth to be treated and cared for as one’s own child, including complete rights of inheritance.” Huiothesia literally means, “to place as a son.”
“Adoption” clearly indicates that a Christian is a member of God’s family. In the Roman culture, the adopted son or daughter had four major changes: a change of family, a change of name, a change of home, and a change of responsibilities. 
Most importantly, by using the word “adoption,” God emphasizes that salvation is permanent for the Christian, which is why it appears only in the Church Epistles. Some versions translate huiothesia as “sonship,” but we believe that is not as good as “adoption.” While it is true that someone adopted into the family attains sonship (the status of a son), “adoption” is more accurate to the Greek meaning of the word, and it correctly expresses the fact that the adopted child is permanently placed in the family.
Birth seems so much more desirable than adoption that it is fair to ask why God would even use “adoption.” The answer is that the Romans recognized that when a baby was born, “you got what you got,” whether you liked it or not. This would include the sex of the child, birthmarks, etc. Thus, according to Roman law, a naturally born baby could be disowned from the family. However, people adopting a child knew exactly what they were getting, and no one adopted a child unless that specific child was wanted as a family member, so according to law an adopted child could not be disowned. He or she was permanently added to the family. Many early believers were Roman citizens, and using the word “adoption” was one of God’s ways to let the Church know that He chose the children brought into His family, and they could not be taken from it. The Roman historian William M. Ramsay writes:
“The Roman-Syrian Law-Book…where a formerly prevalent Greek law had persisted under the Roman Empire—well illustrates this passage of the Epistle. It actually lays down the principle that a man can never put away an adopted son, and that he cannot put away a real son without good ground. It is remarkable that the adopted son should have a stronger position than the son by birth, yet it was so.” 
Roman customs and laws differed from those of the Jews, and it is by understanding Jewish laws and customs that we see why “birth” is used in Peter and James, and “adoption” is used in Romans, Galatians, and Ephesians:
“Among the Jews, adoption had no importance, and hardly any existence. The perpetuity of the family, when a man died childless, was secured in another way, viz., the levirate. Only sons by blood were esteemed in the Hebrew view.” 
The “levirate” that Ramsay refers to was the law stating that if a man died childless, his wife was to marry the man’s brother, and then her oldest son would be counted as the child of the dead man and carry his name (Deut. 25:5-10; Mark 12:18-27).
God made salvation permanent for Christians, which was radically different from before the Church started on the Day of Pentecost. He worked very hard to communicate that change to His Church, which is composed of both former Jews and former Gentiles (when a Jew or Gentile believes, he or she does not lose his nationality, but in God’s eyes is now a Christian, a new creation in Christ). Thus, in Scripture that has a distinctively Jewish flavor, such as Peter and James, God speaks of “birth” (anagennao, 1 Pet. 1:3, 23; apokueo, James 1:18), because birth and genealogy were very important to the Jews. They would immediately understand that a child “born” into God’s family was a permanent member of His family. God also uses a word for “birth” (paliggenesi) in Titus 3:5. It is noteworthy that all three of these Greek words for birth are unique to writings to the Christian Church, another indication of the permanence of Christian salvation.
However, in books such as Romans, Ephesians, and Galatians, which were addressed to people with a Gentile background, He also speaks of “adoption.” The same truth is communicated by both terms: the Christian becomes a permanent member of the family of God, because he is forever sealed in Christ (Eph. 1:13), and has a guaranteed hope (2 Cor. 1:22; 5:5; Eph. 1:14; NIV, ESV). While no verse in the Old Testament even hints that one day God would make salvation permanent, the permanence of salvation for Christians is the hallmark of the Sacred Secret.
This total change to permanent salvation is clearly taught in Galatians 4:1-5. The first three verses of the chapter show that before Jesus came, though the people of God were heirs, they were equal to slaves, being under guardians and enslaved to the basic principles of the world. God’s equating Old Testament believers to minor children equal to slaves is very important, because a slave is not guaranteed a place in the family. Galatians goes on to say that when the fullness of time came, God sent His Son (3:4) so that we might receive “adoption” into His family.
Galatians 4:5 then says: “[God sent His Son] in order that he might redeem those who were under the law in order that we might receive the adoption.” The two “in order that” clauses show that for people to be adopted into God’s family, Christ first had to redeem them, and before Christ redeemed them they were under the law. Without Jesus paying the redemption price, no adoption was possible. Thus no Old Testament believer was adopted into God’s family because adoption was not available yet. Adoption was available only after Christ died, and God started bring people into His family by “adopting” and “birth” on the Day of Pentecost, 50 days after Christ died on the cross. Thus, permanent salvation was not available until Christ died, and was first made available when the Church started on the Day of Pentecost. For further study on the permanence of Christian salvation, see our book, The Gift of Holy Spirit: The Power to be Like Christ, Appendix A: “The Administration of the Sacred Secret.”