Christopher Heard at Higgaion has a good post that critiques the exegesis in an article from the Expository Time. Although I agree with most of what he says, I did want to make one comment.
Chris points out that, contrary to what the article says, most offerings in the Bible are not todah (thanksgiving) offerings. He says that the todah is found only in Leviticus 7:11-18 (he has a typo that calls it chapter 17 instead) and is to be understood as a subset of the shelam (offering of well-being).
I would have to disagree with this. It seems to me that the todah is not actually a type of sacrifice. It is not listed as a sacrifice in Leviticus 1-7, and the same word simply has the meaning of “thanksgiving” in numerous passages. Instead, todah is a reason for offering any number of sacrifices.
What we have in Leviticus 7:11-18 is not the regulations for the todah but the regulations for a shelam that is offered for a thanksgiving. But other types of sacrifices could be offered as a todah as well. Amos 4:5 calls for todah of leavened bread, and this certainly is not a shelam, since the shelam must be an animal. Of course, Leviticus 2:11 forbids the use of leaven in the grain offering, so it is unclear to what type of sacrifice Amos 4:5 refers. And although the burnt-offering is never connected with the word todah, it is likely that thanksgiving was one of the reasons for offering the burnt-offering as well.
Two types of offering could not be considered for todah, however. These are the purification offering and the guilt offering, which were brought to purify the temple and the believer, not for thanksgiving.
In other words, Chris is correct that Numbers 15 does not mention the todah, but it does mention several types of offerings that could be offered for thanksgiving. But the passage in Numbers 15 does not specifically focus on its function as thanksgiving. Instead, it lists a number of reasons for sacrifice, such as fulfillment of a vow or as a freewill offering. Obviously, these reasons for offerings do not support the author’s position, which is the point of Chris’s post.