The case against חטּאת and the piel of חטא referring to a sin offering does not make purification offering the necessary alternative. When sin is being addressed by the חטּאת, it connects with moral impurity only in the exceptional case of the Day of Atonement. Not impurity but defect/deficiency provides the right level of generality for making sense of the whole range of texts. Unless the view in Ezek 43:26 is an unstated assumption of all the Pentateuchal cultic texts, it seems likely that the חטּאת can deal with a deficiency that is neither of impurity nor of sin. Despite the mt exclusive focus of non-cultic uses of חטּאת on sin, the wider uses of the חטא root open up a place for a cultic use where blame is not necessarily involved.