Paul is in prison, yet he preaches spiritual freedom.... very cool.
Somehow we are conditioned to say, "Tell me what to do'". We want the list of do and do not. This is the imperative. But Paul doesn't start there, he starts with who we are in Christ. That is the indicative. What we do must flow out of who we are. Starting with what to do results in a works based salvation, a works based religion. What God and Christ and the Holy Spirit have done and continue to do for us has nothing to do with what we do, but with who we are.
I am a child of God, bought with the price of Christ's death, living in the power of the Holy Spirit, looking forward to an eternity in Heaven. Because of what He has already done and who I am, I serve Him with my actions, I seek to please Him, I do good things.
That is the freedom of Christ. Not freedom to do whatever I want, but freedom to be able to to love Him, to please Him, to obey Him. He saved me. I had nothing to do with it.