I've been doing a bunch of reading as I revise the "Atonement" chapter of my book, and recently this has focused on the Levitical sacrifices.
These sacrifices are often cited as a defense of Penal Substitution. The claim is that a perfect animal has the sins transferred to it and is then killed, bearing the punishment of the sinner.
I already knew of a few problems with this effort at defending PSA, but closer reading opened up some issues quite new to me that I thought I would share. I'll start with the ones that I had already pointed out and move to the new ones.
1) The idea of sins being moved to the animal would upset the entire sacrificial system, as then the animal would no longer be blemishless and would be an unworthy sacrifice.
2) An animal that had sins transferred to it would contaminate the temple and its altar. The sanctity of the temple was so important that someone who was ritually unclean (say, from menstruation or touching of a corpse) would be killed if they even stepped foot inside. (Several examples of this, Numbers 19:13 is one).
3) Sometimes atonement was made with grain or simply money, where it is harder to understand how there was any transfer of sin. In the case of Leviticus 5:11, this is clearly a sin offering. In other cases the word 'atonement' is used even if it is not called an offering. (Exodus 30:15, Numbers 31:50)
4) The Bible clearly states that the PRIEST, not the animal, bears the iniquity of Israel. [For example, Leviticus 10:17 and Numbers 18, both of which speak about very general affairs.]
5) That the animals used in the sin offerings retained their perfection is made clear in what happened to their remains. Their blood was often taken into the more holy places of the temple, even the holiest of holies. Their flesh was EITHER burned outside in a ceremonially clean place OR actually had the affect of purifying those that ate it! (Leviticus 6:18, 27) This is the only case of a sacrifice making an unclean person clean by eating and is a presaging of the Eucharist. In other sacrifices [sacrifices that were not for sin], it was the opposite: you had to already be clean to eat it, and if you weren't, you were killed. Another example of this is the red heifer, whose ashes would consecrate someone well after it had been sacrificed.
6) This last remark actually shows again that the priests bore the iniquity, because the eating of the flesh occurred only after a sin offering was made. The priests in question were not unclean for anything they had done, but yet eating the sin offerings made them clean.