17 And if a soul sin, and commit any of these things which are forbidden to be done by the commandments of the Lord; though he wist it not, yet is he guilty, and shall bear his iniquity.

18 And he shall bring a ram without blemish out of the flock, with thy estimation, for a trespass offering, unto the priest: and the priest shall make an atonement for him concerning his ignorance wherein he erred and wist it not, and it shall be forgiven him.

19 It is a trespass offering: he hath certainly trespassed against the Lord.

At the start of the chapter we were shown smaller offenses, primarily sins of omission. Here at the end, it now talks about the actual breaking of the commandments, which would be a sin of commission, though still done in ignorance.

Perhaps an example of this would be when we are caught in a shameful situation and immediately minimize it out of a self-preservation instinct, only realizing later that we have told a lie. Or perhaps we bore witness that we actually thought was true, only to learn later that we had propagated falsehoods. Or we might have a culture that insists that fornication is common, expected, and shameless, and it is only after reaping the painful consequences of such choices that we start to realize that we have sinned.

There is an important lesson here: intent is not all that matters, sometimes an act is just wrong. That isn’t to say that intent does not matter at all. Malicious harm is worse than accidental harm, but both are harm either way. We can both give special weight to intent, while also acknowledging the fundamental wrongness of the act regardless of intent. And that is what the sacrifice in these verses seems to be for. Atoning for the act, even in absence of intent.