In a 2003 article in Perspectives in Religious Studies, Jason Whitlark gives this sharp summary of the classical Greek linkage between charis (grace) and reciprocity:
“(1) Charis’s contextual environment was one of reciprocity, not only among humans but also with the gods. (2) Charis was often merited by the character and achievements of an individual. (3) Unreciprocated charis usually resulted in retribution and dissolution of the relationship. (4) Consequently, the giving of charis created indebtedness in the recipient, and only the persevering gratitude of the recipient of charis would guarantee that the debt would be remembered and requited at an indefinite future time. We can see, because of the intimate association of charis with positive reciprocity, how the semantic field of charis includes both the favor or benefit bestowed and the gratitude or thanks given in return” (333).
He looks at some other ancient evidence (from Greco-Roman principles of benefaction and Philo) and then asks whether Ephesians displays this same understanding of charis, which would result in a Pauline version of covenant nomism. His answer is No, and the specific difference is that for Paul grace is not merely the beginning of a relationship but a continuous gift that enables the recipient of charis to walk in obedience. Whitlark says:
“In Ephesians, the bond between God and His elect is established by His charis. Moreover, His charis not only admits them into a relationship but maintains the bond of that relationship. The saints’ perseverance in holiness, blamelessness, and love are a result of God’s inward working. God’s bestowal of charis upon His rebellious creatures transforms them into obedient children re-created to do the good works that God has prepared for them. God has no need of reciprocity or the charis-convention to maintain the bond between Him and His elect” (355).
Were God like a Benefactor bestowing grace, the recipients would owe a debt of gratitude, and God would maintain “the feeling of indebtedness to Him in them.” Reciprocity “works on the premise of paying back gratuitous acts as though they were debts.” Treating God’s grace on the model of reciprocity would imply that the beneficiary finally, eschatologically, would justify himself “by their repayments of gratitude” (356). Further, if God’s grace were seen as imposing a debt, then “this would discourage the Christian from seeking continually new supplies of charis from God because he or she has not repaid the initial charis that he or she is indebted for” (356).
I think the model works better than Whitlark suggests, but I agree that the key difference between Paul and the reciprocity/covenant nomism model is the Spirit’s continuing work. Grace doesn’t just get us in; it keeps us in. Perhaps we can even retain the idea that God’s graces impose debts on the recipients, so long as we immediately add another point: The basis of our relationship with God is the forgiveness of debts not only at the outset, when God forgives the ungodly, but every day. Every day God bestows gifts that leave us in His debt; then He forgives those debts. He does not enslave but frees.