Leviticus chapter 4 discusses the Korban Chatat – sacrifice for sin. We learn there that this sacrifice was only brought for unintentional transgressions. (For example, someone who wrote, but didn’t realize it is forbidden to write on the Sabbath).
Rabbi Yitzchak Arama explained that intentional sin involves both our body and our mind/soul. Only the body is implicated in unintentional sin because there was no conscious intent to sin. Therefore, he explains, a physical sacrifice could atone for an unintentional sin since only the body was involved in transgressing. However, a physical sacrifice could not atone for a deliberate sin because it could not correct an evil intent rooted in the soul.
