What makes a person a child of God?   Paul had grown up to believe that circumcision and keeping the Old Testament law had secured his place in God’s family (Philippians 3:4-6).  But after Paul met Jesus, he realised that Jesus Christ had fulfilled and replaced the law.  Only faith in Jesus could bring people into His family (Galatians 2:15-16).  That meant that Gentiles (non-Jews) could be welcomed by God as equals with Jewish-background believers (Galatians 3:28).  But anyone, including Jews, who refused to believe that Jesus died as a sacrifice for their sins, could not be included in God’s family.
 
Before Christ, circumcision was the mark of being a descendent of Abraham; it was a sign of being in the patriarch’s family (Genesis 17:9-14) and accepting the privilege of being under God’s covenant.  But each circumcised baby boy had no choice; neither could circumcision ever generate faith in God’s Messiah. Abraham’s faith was real (Genesis 15:6; Galatians 3:6) but the circumcised religious leaders of Jesus’ day did not believe.  Indeed, Jesus went further to say that although their genetic line came from Abraham, their spiritual father was the devil (John 8:39-47).   

The gospel brought a new family together.  Both Jews and Gentiles who believed in Jesus made a voluntary choice to submit to baptism; it was a true sign of their personal faith in Jesus (Romans 6:3-4).  They had ‘clothed themselves with Christ’: this was a reference to the tradition of a young man being given a special toga (ceremonial Roman costume) to make the transition from boyhood into the full family rights of being an adult in the family.
 
It is the most wonderful privilege to be a child of God when we welcome Jesus (John 1:12).  We do not deserve it; we are not given it by our human parents; we cannot earn it or pay for it.   And, once we are in God’s family, our position or status is no less or more than anybody else’s.  Paul’s message to the Galatians is for us as well: do not go back to trying to earn your place in God’s family, just put your trust in Jesus Christ.  We are called to serve because we believe in Him, wearing His uniform.  It is the family business of the sons of God, who like the Galatian believers, have been freely welcomed by the Father as His much loved children (1 John 3:1).