Galatians 4:1-7 meaning

Paul is giving an analogy to the Galatians. He uses a child that is an heir in the analogy. When this child is old enough, his father will give him an inheritance, and therefore the child will be the owner of everything. But so long as the heir is a child, he does not differ at all from a slave. While a child, he does not exercise the responsibility and authority of being an owner. In terms of responsibility and freedom, both child and slave are equal. Even though the child is the inheritor of his father's estate, he does not yet have the authority that goes with possessing the inheritance.

While still a child, the heir has guardians and managers deciding for him, and showing him how to be mature, until it's time for his father to give him authority over the inheritance. Paul says that in the fullness of the time God sent forth His Son, Jesus. Jesus was born of a woman, born under the Law. That likely means Paul is referring to the children of Israel as those born under the Law. That would fit since the primary subject of Paul's letter is to contest against competing Jewish "authorities" who are trying to convert the believing Galatian Gentiles to live under the Jewish Law.

The Jews who were, like Jesus, born under the Law, can now be redeemed from being under the Law through Jesus. No longer do they have to be like children or slaves, answering to managers. They now can receive the adoption as sons. In this era, Roman children went through two phases of transitioning into adulthood, and receiving the inheritance of helping run the family. This process was called "adoption." This use of the word "adoption" did not apply to the Roman children joining the family, it referred to the ascension of the children to a place of authority. The first phase of adoption was at age 14 when the son would receive voting rights, the right to have a voice. The second phase was to receive property rights, the right to make decisions as an owner at age 25.

Jesus freed the Jews from being like children or slaves under a master, in this case the Law. Instead of the Law telling them everything to do, they are now sons and received the authority to decide on their own. If Jesus freed Jews from being under the Law, would it make any sense for Gentiles who believe in Jesus to come under the Law? Not at all.

Paul includes the Gentile Galatians in the analogy as well. Gentiles were also like children prior to Jesus. But unlike Jews, who are born under the Law, Gentiles were children that were held in bondage under the elemental things of the world. Although the Gentiles were not under the Law, Paul includes Jews in the category of being under the elemental things of the world when he says "we", including himself as being under the sin of the world. Every person begins as a part of the world. The world has its own rules. In order to "get ahead" the world requires specific behavior. As we will soon see, this behavior for the Galatians included various forms of pagan religious worship.

But then, when the fullness of the time came, God sent forth Jesus for the Gentiles as well as the Jews. And just as Jesus made the Jews sons, Jesus also made the Gentiles sons. Like the Jews, the Galatians are no longer like children or slaves. They too are sons. They also are now ready to exercise the freedom and responsibility of being an adult, one possessing the authority to decide for themselves.

The fullness of time refers to the exact right timing of Christ's coming. Rome ruled the Middle East, and had built roads that made travel much easier; Greek was the common language across many different cultures; there were no major wars, due to strong Roman governance, during this time period; the Jews, under Roman occupation, were ready for a Messiah to restore the Kingdom to Israel. All the circumstances surrounding Israel made it the perfect time for Jesus to come, and for the Gospel to spread after His return to Heaven.

God chose this time period, the fullness of time, to send His Son, born of a woman, born under the Law, which points to Jesus's humanity and upbringing under the Old Testament Law as a Jew, so that He might redeem those who were under the Law. He came to free His people, who were in bondage to the law. The goal for this redemption was so that we might receive the adoption as sons.  

How do the Galatians know they are sons? Because of the Spirit. Because Jesus came, Paul says we have the Spirit of His Son in our hearts. Gentiles no longer need to be under the rules of the world as its slave. Gentiles have been adopted as sons as well. Paul tells the Galatians they have the Spirit of His Son leading them to follow God, crying Abba, Father! Abba is a term of familiarity, not just a family connection. It's like calling God, "Daddy." That is our connection to God now, as believers.

Therefore, Paul writes, in light of this adoption, he tells the Galatians they are no longer a slave, but a son; and if a son, then an heir through God. We are sons and heirs to God, because of Jesus Christ, because of the Spirit within us that calls out to the Father. This inner testimony of the Spirit is all they need to know they are adopted as sons.