“What the ‘stumbling block’ is, Nephi did not say at that point, but he had used the identical language earlier to explain that the Gentiles would stumble because the Bible had been significantly altered and was thus lacking ‘many plain and precious parts’ that had been ‘taken out’ of it. (See 1 Ne.13:28–35.)
“In view of Nephi’s earlier … explanation about plain and precious parts being taken from the Bible, we can ascertain that the Gentiles’ great ‘stumbling block’ in the last days would be the lack of knowledge and spiritual understanding because of their imperfect Bible, which is the only scriptural record they have ever had” (Matthews, “Two Ways in the World,” 151–52).