Are we under a debt economy?
No, we are not under a debt economy. We will never put God in our debt, so we cannot work for salvation, not one iota. Salvation is by faith, not works, as Paul writes that the reward is not reckoned of grace but of debt for those who work.
Les teaches that we are not under a debt economy because we can never put God in our debt, and therefore we cannot work for salvation, not one iota. He contrasts Paul and James: Paul says you are saved by faith alone, while James says you cannot be saved without works. The difference is perspective—James looks at it from man's point of view, for if there are no works, we have no idea a man has saving faith. But God looks at the heart like He did with Abraham, who was saved by faith plus nothing. We do not have to do works to prove to God that we have faith, but to prove to our neighbor, we better show works. In Romans 4, Paul adds that to him that worketh, the reward is not reckoned of grace but of debt, yet to him that worketh not but believeth on Him who justifies the ungodly.