The verb cleanse seems strange here. Elsewhere in the Book of Mormon, cleanse is used to refer to spiritual cleansing (from sin, iniquity, unrighteousness, or corruption). In the Book of Mormon, mortality per se is not explicitly viewed as needing cleansing (consider, for instance, Mormon’s arguments in Moroni 8 for why baptism of innocent children is inappropriate). Thus the verb cleanse seems out of place here in 3 Nephi 28:36.
When referring to going from mortality to immortality, there are several possibilities for the verb in the Book of Mormon text:
More specifically, the text here in 3 Nephi 28 constantly uses the verb change to refer to the resurrection as well as the transfiguration of the three Nephite disciples (in attempting to determine what actually happened to their bodies so they would not die):
If cleansed is an error for changed in verse 36, it did not occur when the text was transferred from 𝓞 into 𝓟 or from 𝓞 into the 1830 edition since both those sources read identically here. Nor does the error seem like one that depends upon Oliver Cowdery mishearing Joseph Smith’s changed as cleansed. More probable is the possibility that Joseph himself misread the word. Visually they are quite similar, with h lining up with le and s with g:
changed CHANGED
cleansed CLEANSED
Perhaps the misreading was also facilitated by the reference in the previous verse to the judgment of God, which speaks of “an offended God who hath been trampled under feet of men” (3 Nephi 28:35), thus implying filth and dirt and perhaps suggesting cleanse for the verb. It’s also possible that the visual similarity of immortality to immorality could have prompted the notion of uncleanliness. (As evidence for such lexical interference, see under Alma 40:2 for the occasional change of immortality to immorality in the text.)
This emendation, replacing cleansed with changed, has been independently suggested in a number of personal communications, from Ross Geddes (3 November 2004), David Calabro (17 November 2005), and Grant Hardy (5 November 2007). The critical text will accept changed as the original reading for this passage since cleansed seems quite inappropriate.
Summary: Accept in 3 Nephi 28:36 the emendation changed, which Joseph Smith apparently misread as cleansed when he dictated the text to Oliver Cowdery (the presumed scribe here in 𝓞).