The Book of Mormon is a Jewish book. This has become increasingly clear to me as I have studied it in much detail while learning more of ancient Israelite culture and language. I mean "Jewish" in a broad sense, since Lehi was from the tribe of Manassah, but he came from Jerusalem and the inhabitants there at the time are generally referred to as Jews. This is what Nephi does too.
I have charity for the —I say Jew, because I mean them from whence I came. (2 Nephi 33:8)
This post only gives one example of the Book of Mormon as a Jewish book by which I mean, the Book of Mormon is telling the story of a people with Jewish heritage. There are many other examples here.
There is a Jewish idea (and ancient Near Eastern idea in general) of guilt from homicide associated with blood pollution. For instance, Moses kills an Egyptian and flees to Midian. Upon his return many years later, he is still carrying the guilt and undergoes a ritual that seems rather strange to us in Exodus 4:25-26, involving blood. The NRSV cultural backgrounds study Bible explains:
The idea may be that, even though Moses is free in a legal sense to return, he still carries about on his person a kind of spiritual or religious pollution as a result of the homicide— a pollution that must be purged. In the case of homicide, the pollution is referred to by the Hebrew word dam (“ blood”); the perpetrator has been contaminated by the victim’s blood. This notion of blood contamination turns up in ancient Greece and Mesopotamia as well. An Assyrian text from the mid-600s BC declares that the perpetrator of a homicide must make a payment (what is really a ransom for his own life) to the victim’s family and in so doing “wash the blood away.” A text from Mari (c. 1800 BC) refers to a “criminal who is polluted with that blood (shed in murder).” In ch. 4, Yahweh cannot allow Moses to emerge from his place of asylum unless the contamination is purged.
Notice how Alma 5 is completely aligned with this line of thinking.
I have noticed that the Book of Mormon frequently applies secular Jewish traditions to our relationship with God. I have written about several such examples before. "Cut off from among the people" in the Old Testament becomes "cut off from the Lord's presence" in the Book of Mormon. The tradition of a kinsman-redeemer in the Old Testament is applied to our redemption from sin in the Book of Mormon. Etc. In Alma 5, the idea of blood pollution reflects ancient Jewish culture but also applies on a more spiritual level, in this case judgment day.