Paul reminds us that, through the Gospel, we are children of God: we are no longer servants of the law, under which God was unapproachable. We are now allowed a free, close and intimate relationship with our Father that could not be possible before the perfect atonement sacrifice. In Jesus, the old has been fulfilled and the new has indeed begun.
Circumcision was the old covenant sign that we had entered into a legal servant relationship with God. And, by the way, it was for males only. Under the law, there were certain rights and privileges allotted to men. Now, under the new covenant, baptism replaces circumcision as the sign that we have actually entered into the family of God. And it’s for all who have been united with Christ. The major difference here is that we now have all the rights and privileges to which heirs, not servants, are entitled. The whole point Paul is making in these verses is that accepting Jesus as our Lord and Savior, and relying on him alone for justification and salvation, admits us into the heavenly family of our Father with no discrimination.
On earth, there may still be slaves, as viewed by men. But in God’s sight, there is absolutely no distinction between His children. There are still those who were born into Judaism and those who were not. And we will still be male and female, otherwise the human race itself would die out. But unlike those who lived under the law, everyone who puts his or her faith entirely in Jesus Christ, has equal access to all family privileges, without prejudice, distinction or partiality. God has a lot of children, but no favorites.
For you are all children of God through faith in Christ Jesus. And all who have been united with Christ in baptism have put on Christ, like putting on new clothes. There is no longer Jew or Gentile, slave or free, male and female. For you are all one in Christ Jesus. Galatians 3:26-28 New Living Translation (NLT)