Rom 1:14 I am debtor both to the Greeks, and to the Barbarians; both to the wise, and to the unwise. 15 So, as much as in me is, I am ready to preach the gospel to you that are at Rome also. 16 For I am not ashamed of the gospel of Christ: for it is the power of God unto salvation to every one that believeth; to the Jew first, and also to the Greek. 17 For therein is the righteousness of God revealed from faith to faith: as it is written, The just shall live by faith.
The Apostle Paul considered himself under obligation or a debtor to preach the Gospel to all people which is also the Great Commission, “Go ye into all the world, and preach the Gospel to every creature….” This concept of being a debtor, one who owes, one who is obligated, and one who must seems like a hard thing to reconcile for those who claim they are under grace and are under no obligations. Keep in mind that the Apostle Paul who wrote this in Romans is the same Apostle who was given the grace message or the Gospel of the grace of God to testify of Acts 20:32.
I believe that when a person receives a revelation of the true grace of God (1 Peter 5:12) they come to realize they are a debtor to Jesus for all that they are and have. 1 Corinthians 4:7 says,”For who maketh thee to differ from another? and what hast thou that thou didst not receive? now if thou didst receive it, why dost thou glory, as if thou hadst not received it?” What do we have that we didn’t receive?
This attitude of being a debtor is a key to being a grateful person. Ungrateful people seem to carry a chip on their shoulder that someone or life owes them. We cannot pay for our salvation but what more does God have to do than what He already did in Christ for us? He doesn’t owe us but we are indebted to Him with a debt of lifelong gratitude.