Bob Dylan wrote that song
‘You got to serve somebody‘.
That statement is true.
This verse about being free, Romans 6:22, follows the verse about how our old life had a slave driver leading us to destruction and death.
But now – 
Those who have accepted Christ as their Lord, not only have a kind and loving master who does not want to harm them as captives of the world,
but they will also serve a ‘Father’ who wants them to enjoy an eternal life with him.