No obligations | Romans 8:12-13

So then, brothers, we are debtors, not to the flesh, to live according to the flesh. For if you live according to the flesh you will die, but if by the Spirit you put to death the deeds of the body, you will live. Romans 8:12-13
Being a "debtor" to the flesh means you owe your flesh something. Sadly, what we owe our flesh is destruction; the wages of sin is death (Rom 6:23). And all too often, that's what we give it. We choose the things that lead to death, and we justify it by telling ourselves that's what we deserve. And the more we choose sin, the more sense this starts to make.
Another glass of wine? I know I shouldn't, but why not? I'm already drunk. Too late for me.
Another visit to that website? I'll hate myself later, but why not? I'm so far down this road already...
I know I'm lying about what I did, but who cares? I'm condemned already.
I know it's Sunday morning but I might as well just sleep in. There's no hope for me after the way I've lived this week.
The flesh is a master that drives us towards the deeds of death and then tells us that since we did that there's no hope for us. We're already going to get what we deserve, so might as well do it again.
But for a believer, this is no longer necessary. You are no longer enslaved, indebted, given over to your flesh. The wages of sin have been paid: to Jesus. The gift of God is eternal life: to you, through Jesus. You have the Spirit of Jesus inside you to live according to eternal life. And the Spirit of God is here to guide, empower, and train your spirit to govern your flesh, to lead your flesh into deeds of eternal life. With the Spirit giving life to our spirits, we don't have to live according to what the flesh dictates anymore. We can dictate to our flesh according to the Spirit.
I think this idea of being debtors to the flesh goes back to the idea that the punishment for sin is sin. In Romans 1, God sees that people are wicked and have no desire for him, and his punishment for their idolatry is more idolatry. They will dig their own graves by pursuing wholeheartedly the very thing that is going to condemn them to death.
There is acute justice in this response from God. Sin is its own punishment.
Guilt can be a force that spurs you into more guilt. The cycle where one sin makes you feel like you owe yourself another sin. You're punishing yourself with more sin. Your desire for justice is leading you to do this. You feel indebted somehow, like you have to pay someone off, but the only thing you can think to pay off is your sin and the only one you can find who is accepting the currency of condemnation is your own flesh. So you sin again, knowing that it will lead you ultimately to the punishment you deserve. This is the cycle, the path of doom.
This isn't God's way of dealing with the sin of one whom he has chosen, called, justified, and whom he is preparing for glory. The Spirit gets us off the Romans 1 path of slavery and onto the Romans 8 path of sonship.
Next time you find yourself thinking "justice" and choosing out of justice to punish yourself with more willful sin, you need to understand that this is not doing God any favors. There is nothing noble or true about a son of God digging up corpses that already have died and gone down into the grave with Christ. That's just morbid.
Your sins have died with Christ. When you falter and fail and sin, all that's left to do is just get up and walk away. Ask God for forgiveness, and thank him. Deal with the people you've hurt. And then move on. There is no courtroom, there is no trial, there is no condemnation.
And no matter how many times you cycle back into debt and make the mistake of heaping one sin on top of another, no matter how high that pile gets before you remember - oh, yeah! I don't have to do this! - God will be there to forgive you and restore you every time. Just put that whole death trap to death.
So much of our struggle with sin is not something we're doing out of pleasure, but out of pain. The pleasure of sin is a fleeting, short-lived thing, and those who are really lost in it aren't happy. They're miserable. But sin is cruel. By the time it has us where it wants us, the lie that we're beyond hope has well taken root. As that lie grows, it doesn't matter how miserable we get. The more miserable, the more we sin. We choose darkness and death because it's what we deserve, not because we truly, ultimately, enjoy it. We can't even remember how it felt to be alive, to want to live. Somehow, that feels just. And it is. But as I said before, it doesn't accurately reflect what God has done for you. His justice redeems.
For God did not send his Son into the world to condemn the world, but in order that the world might be saved through him. (John 3:17)
Claim it. Think back through the past week. Are there any sinful habits you know you're doing...just out of habit? Things you know are making you miserable, heaping guilt into your life, but you tell yourself you deserve that misery - and so you do it again, to punish yourself. I bet you think God is watching you with a judgmental look on his face, disgusted, disappointed. I bet you imagine he's the one making you feel guilty. Believer, what if God is watching but not condemning? What if he's thinking, "Neither do I condemn you. Go, and from now on, sin no more" (John 8:11)? Talk to him about this. Tell him you believe he's that gracious. And tell him you accept his guidance by his Spirit in your spirit. Resolve to walk in step with the Spirit and lead your flesh into life. Put this phrase in your pocket: walk by the Spirit.
But I say, walk by the Spirit, and you will not gratify the desires of the flesh. For the desires of the flesh are against the Spirit, and the desires of the Spirit are against the flesh, for these are opposed to each other, to keep you from doing the things you want to do. But if you are led by the Spirit, you are not under the law. (Gal 5:16-18)