With Paul, there’s a thread running through the whole letter, a building argument, and so sometimes splitting it up into portions can make its overall meaning less clear. So why does Paul veer off into circumcision and slavery in the middle of a chapter about sex and marriage?
The main point is don’t be pressured to change the status you had when you became a Christian.
In Galatians 3:28, Paul puts forward 3 pairs of distinctions Jew/Greek, slave/free and male/female and tells us the distinctions are nothing in Christ Jesus. Is belonging to Jesus more important than anything else? Is it more important than being a Jewish believer or a Gentile believer; is it more important than being a slave or free (note Paul is not commenting on whether slavery is right or wrong – it was so embedded, it was like running water), is it more important than your gender?
Our social and cultural distinctions are as nothing compared to being in Christ.
So Paul mentions circumcision – people exercised and used public baths naked, so being circumcised or not was obvious. Some Jewish believers might have felt pressure to become uncircumcised and vice-versa.
Then Paul mentions slavery – get free if you can, v.21. But being in Christ is more important than being a slave or being free. Don’t sell yourself into slavery.
Remain in the status you were at conversion. Likewise, don’t be pressured to marry or not marry.
A change of status – circumcised/uncircumcised; slave/free; male/female; married or single is no longer our ultimate goal, or our ultimate destiny. Being a Christian and found in Christ is. That is our fundamental identity and our spiritual and mental health depends on it.
Is belonging to Jesus more important to you than anything else?