Updated: Oct 18
In the regulations that describe the sin or purification offering in Leviticus 4-5, there is an important word that sets the context: unintentionally. The purification offering is circumscribed by a particular kind of sin, an “unintentional sin.” What does this mean? “A sin of this type may result from two causes: negligence or ignorance. Either the perpetrator knows the law but unintentionally violates it as in the case of accidental homicide (Num 35:22ff; Deut 19:4-10; Josh 20:2-6, 9), or he acts without knowing he did wrong. Some illustrations of sins in this [latter] category would be: Gen 20:9 (Abimelech's complaint to Abraham); Num 22:34 (Balaam: "I have sinned. I did not know you were standing in my path")” (TWOT, שְׁגָגָה).
This qualification of the kind of sin that could be atoned for by the purification offering then suggests that there are other kinds of sins which cannot be atoned for—at a minimum through this offering. What is then mentioned is the kind of sin described in Num 15:30 (ESV): “But the person who does anything with a high hand, whether he is native or a sojourner, reviles the LORD, and that person shall be cut off from among his people.”
A natural question that then may arise is this: are “unintentional sins” and sins committed “with a high hand” the only two options? What do we do with intentional sins which we might not think rise to the level of something that “reviles the Lord”? I have read and heard it said that the OT sacrificial system did not have a provision for atoning for anything other than “unintentional” sin. This observation is then highlighted as a deficiency in the sacrificial system that is filled in, as it were, in the new covenant inaugurated in Christ’s blood. And so, the answer to our question is “yes, there are only two options.”
But I don’t buy that line of thinking. I think it makes too much of the word “unintentional” and misses some of the significance of the reparation offering, which is described in the beginning of Leviticus 6. Moreover, I think we need to appreciate the organic continuity between the Old and New Testaments, which in this case would mean an acknowledgement of implied grace in the sacrificial system.
To be sure, with the advent of the Messiah, we see and experience grace upon grace. We also see in Christ the fulfilment of something, the sacrificial system, that could not effect full and final atonement. I would argue that the defect of the sacrificial system is not in lacking a category for certain kinds of sins but in its inability to fully and finally deal with the power of sin, death, and the devil.
In my mind, Jesus did not add something new or entirely foreign to the old covenant in his coming so that a category of sin which was not able to be forgiven could now be forgiven. Rather, the shadows and types of the Messiah’s grace are seen for both unintentional and intentional sin in the sacrificial system. This point is made in Lev 6:1-7, which deals with the reparation or restitution offering. Those verses address the issue of swearing falsely: “If anyone sins and commits a breach of faith against the LORD by deceiving his neighbor … and lied about it, swearing falsely…” This is clearly not an “unintentional” matter. Thus, the OT scholar Gordon Wenham comments,
What is striking about this provision is that although the offense was blatant and deliberate, perjury in a public court, yet sacrificial atonement was permitted. The other reparation offerings were for inadvertent sins. So too were the purification offerings, though these were also acceptable for sins of omission. It seems likely that atonement for deliberate sins was possible where there was evidence of true repentance, demonstrated by remorse (feeling guilty), full restitution, and confession of sin.
All in all, the key for both the purification and reparation offerings was a softened conscience, so that the kind of sin rests more with the attitude of the heart than the nature of the offense. To be sure, our Lord does describe a kind of sin committed with a high hand—the unforgiveable sin which is the sin against the Holy Spirit. Beyond that what Christ did was fulfill the hopes of cleansing and atonement for every other kind of sin once and for all. The extent of the forgiveness of sin covers all kinds of sin, then, and for that we can give him great praise and thanks.
 Gordon J. Wenham, The Book of Leviticus, The New International Commentary on the Old Testament (Grand Rapids: Eerdmans, 2009), 108–9.