When an action is undertaken, the trace or seed of it enters the mind stream and its consequences appear when the seed ripens. Furthermore, if, for example, you give yourself permission to kill one mosquito, you will hardly pause when the opportunity arises to kill another. If that is the case, is atonement a fool’s errand? Don’t we just have to wait and endure the consequences later? Is the die cast for both consequences and future behavior?
Perhaps this discussion is getting ahead of the curve. Many people don’t consider or agree that actions even have consequences. But to counter, as a manifestation of will (mind), whether conscious or not, an action is a cause and all causes have effects. To explain further, the arising in the mind of an intention moves to create an action. Intention causes action. So an action is both an effect and a cause. That is the simplest presentation of the Law of Karma. The effects come after, though for beginners which effect is the result of which action is hard to discern.
Atonement, too, is a mindset. Following this logic, if intention is a cause of action, then taking the mindset of atoning for past actions leads to new kinds of actions, and potentially actions that uncouple the linkage between previous actions and their results, though this clearly is in the realm of spiritual discipline. Deciding not to eat Twinkies does not necessarily purify ones past.