You are using a 21st century understanding of slavery, not a 1st century understanding. A slave when that text was written CHOSE to be a slave unless they were part of the plunder in battle. It is clear the context supports one choosing to become a slave to sin.And yet, all sin. And since all sin, all are slaves to sin (not servants.. the word is "doulos" and it means "slave")
The slave obeys the master. The slave does the will of the master.
And Paul's point is Romans 6 is that since your will has been freed from the power of sin by Jesus Christ, don't yeild yourself to sin anymore. You have died to sin, live to Christ.
peace to youraying: