Here the 1837 edition changed the which to who, which means that the original which was interpreted as referring to Christ; the change was probably made by Joseph Smith in his editing for that edition, although the change was not marked in 𝓟. However, it is possible that the relative pronoun which actually refers to “faith in Christ”—that is, Alma, Amulek, and Zeezrom taught faith in Christ. Elsewhere, the text refers to Alma and Amulek’s faith in Christ when they were freed from the prison in the city of Ammonihah (Alma 14:26, 28). And Alma, when healing Zeezrom, refers to Zeezrom’s faith in Christ (Alma 15:10). Alma was accompanied by Amulek and Zeezrom on his mission to the Zoramites (Alma 31:6), and Alma’s chief discourse there was on faith (Alma 32–33). Finally, Alma admonished his son Helaman to “preach unto them repentance and faith on the Lord Jesus Christ” (Alma 37:33).
The Book of Mormon text has no other phrases that could be interpreted as equivalent to the phraseology “to teach Christ” or “to preach Christ”—that is, with Christ as the direct object of the verb teach or preach. The closest is in 2 Nephi 25:26 (“we preach of Christ”). There are five references to “preaching faith”, including Alma 37:33 mentioned above (the others are in Mosiah 18:7, 20 and Mosiah 25:15, 22). Interestingly, there are no instances of “teaching faith” in the Book of Mormon text (except possibly here in Helaman 5:41).
The King James New Testament has numerous references to “preaching Christ”, including two that are syntactically similar to the expression in Helaman 5:41 (especially the first one):
The New Testament, on the other hand, has no instances of “teaching Christ”.
Of course, the critical text of the Book of Mormon will restore the original which here in Helaman 5:41 no matter whether this relative pronoun refers to Christ or to faith in Christ. In Early Modern English, which was used to refer to persons, as in “our Father which art in heaven” (in Matthew 6:9 and originally in 3 Nephi 13:9). The original Book of Mormon text had many instances of which with the meaning ‘who(m)’, just like the King James Bible. For a complete discussion, see under which in volume 3.
Summary: Restore which in Helaman 5:41; in this instance, which probably refers to faith in Christ since Alma and his missionary companions consistently taught faith in Christ; the specific expression “to preach Christ” or “to teach Christ” is foreign to the Book of Mormon text.