What are the obligations of being children of God? What are the indications that you are a child of God? These are at least two questions that these verses evoke. Paul is making the argument that as recipients of the grace of God in Christ Jesus, we have some obligations or debts. And if we are truly children of God, these obligations will be the evidence of who we are.
Paul compares and contrasts the unbeliever’s life of the flesh with the believer’s life in the Spirit throughout the first 16 verses of this chapter. Believers walk according to the Spirit, fulfill the requirements of the law, experience life and peace, have Christ living in them, are indwelt by the Spirit of God, and put to death the things of the body. These are the obligations of being a child of God.
Unbelievers, on the other hand, walk according to the flesh, set their minds on the things of the flesh, are at enmity with God, cannot please God, do not have the Spirit of God in them, and will die in their sin.
The use of the word “debtor” in verse 12, conjures up ideas of “duty” and “obligations,” but this should not be misunderstood to be requirements for salvation, but rather proof of our salvation. If we are truly born again, these obligations will be our delight and joy, for this is how we serve Him whom we love with all our hearts. This is our pleasure. Delighting in God is what we live for.