"Oh to grace how great a debtor
Daily I'm constrained to be."
Can grace incur a debt?
Paul says, "NO!"
"I do not nullify the grace of God, for if righteousness comes through the Law, then Christ died needlessly" (Gal. 2:21)
The verb translated "nullify" (ἀθετῶ) is in the present tense, indicating an ongoing activity. In classical Greek, it meant to set aside a treaty or to break faith with someone. The LXX uses it to translate a variety of Hebrew words in the Old Testament. It refers to profaning something that God considers holy, such as the sacrifice (1 Sam. 2:17) or the law of God (Ezek. 22:26). According to Ezekiel, the priests profaned God's law by making no distinction between the clean and the unclean. They despised God by profaning the holy things of God (NIDNTT, 1:74). In the Greek papyri, the verb was used for the cancellation of loans through repayment (M&M, Vocabulary, 12).
Paul uses the same verb later in Galatians, referring to a covenant once ratified, which "no one sets aside (ἀθετεῖ) or adds conditions to it" (Gal. 3:15). Jesus says, "He who rejects (ἀθετῶν) me ... has one who judges him" (Jn.12:48). Seeking to achieve righteousness by obeying rules and regulations, Paul says, annuls or renders inoperative the grace of God. Holiness by law-keeping is a rejection of Christ's death for us. If we seek to be righteous by the law after accepting God's grace, then "Christ died needlessly" (δωρεὰν). The adverb means without reason or to no purpose (BAGD, 210). The death of Christ becomes superfluous - unnecessary - if we can achieve righteousness by obeying the law.
The conduct of Peter is the context of Paul's statement. God saved Peter by grace alone, but Peter slipped into law-keeping for his sanctification. He implied that the Gentiles had to do the same by following the Jewish dietary regulations to maintain right standing with God. Paul argues that Peter nullified or rendered inoperative God's grace through his actions (Meyer, Galatians, 94). Peter rejected the sufficiency of Christ's death by adding conditions to the Christian life. Legalism is a practical rejection of grace and an annulling of the cross as foundational for Christian living.
Suppose that I give my daughter $10,000 in her time of great need. I insist that it is a gift given out of my deep love for her, and she has no obligation to repay me. She says that she is indebted to me and will work to pay me back. Eventually, she cancels the debt by paying me back what I gave to her as a gift. What has she done? She has set aside, rejected, and nullified my gift. When we treat a gift - grace - as a debt, we render the gift invalid. It is no longer grace.
This is what we do when we try to pay God back for His grace freely given to us on the cross. Too many Christians treat the Christian life as a debt to be paid to God for the grace He gave to us. We come to God by faith in His grace but soon turn the Christian life into matters of performance, duty, and obligation. We nullify His grace when the motive for our service is to pay back our debt to Him for His gift. The Christian life is by grace just as much as conversion. Sanctification is just as much a product of grace as justification.
There are two ways to nullify God's grace in our Christian lives (Bruce, Galatians, 146). 1) Grace frees us to sin more (Rom. 6:1). Since we are saved by grace alone, we think we can sin without consequence. The more we sin, the greater His grace. Wrong! May it never be (μὴ γένοιτο, Rom. 6:2). We nullify His grace through our presumptuous sins. 2) Grace motivates us to pay God back. Debt creates guilt. Our Christian lives develop a performance mentality. We think that if we do not measure up to the rules of sanctification, we will not earn God's favor. This too is μὴ γένοιτο! We nullify His grace through the debtor's motive.
We are not debtors to grace because grace cannot incur a debt!
Praise be to God for His indescribable gift!