3 ideas
The novella presents good fortune as coming to Andreas in a steady stream he did nothing to earn: money, a job, a wallet with a thousand-franc note, a free room. Each gift renews his chance to meet his obligation rather than testing him once and closing the door. Grace, on this account, is the pattern of second chances given freely, not a reward for reform.
Andreas never refuses to repay the debt. He fully means to, and fails only through a chain of small, reasonable-seeming diversions: one drink, one meeting, one night in a hotel. Watching this shows how addiction and drift work less through open defiance than through an intention that is postponed indefinitely by the next small pleasure standing in the way.
Andreas is a drunk and a killer, yet he keeps a gentleman's sense of obligation and treats the debt to the saint as a matter of honor. That scruple is what keeps him turning back toward the church. The book suggests dignity and moral seriousness can survive intact inside a person who has otherwise lost everything, and can become the thread by which he is redeemed.