There is much less of an antithetical contrast in this Beatitude. Both sides of the equation appear to provide something that is desirable: the pure in heart and seeing God. The universal meaning for most audiences comes from this positive parallelism between the pure in heart and those who through that personal purity, will eventually see God.
In the context of second temple Judaism, it is likely that there is a very different meaning in that particular context. Once again the pairings tell us about the meaning. Seeing God is obviously nothing to which most humans aspire on this earth, but it was a possibility on at least an annual occasion for one person. The High Priest of the temple would enter into the Holy of Holies in the Temple once a year to offer sacrifice for his own sins, and then for the sins of the people. In that very sacred occasions he entered into the presence of God, he would be in the place where he might “see” God. Of course he must be pure to enter that room. This now requires that we understand how the world pure might have been construed.
The Beatitude has two parts, the noun and the descriptive phrase: pure in heart. The key to this Beatitude is understanding that the culturally understood reference of the phrase “pure in heart” would call to mind Psalm 24:
Psalms 24:3-4
3 Who shall ascend into the hill of the LORD? or who shall stand in his holy place?
4 He that hath clean hands, and a pure heart; who hath not lifted up his soul unto vanity, nor sworn deceitfully.
The obvious connection is the phrase “pure in heart.” What is not as obvious is that the reference would have recalled the context of that phrase in the Psalm. The Psalm uses the pure in heart as the answer to a question, and that question is “who shall ascend into the hill of the Lord? Or who shall stand in his holy place?” This question serves as the model for the Beatitude’s following phrase, the blessing that the pure in heart shall “see God.” Where else might God be “seen” than in the temple, in the holy place of the Lord? This Beatitude is a recasting of the Psalm, reversing the order of the Psalm to fit into the Beatitude format.
Textual: There is only one change in the Book of Mormon text. The Book of Mormon has “all the pure in heart,” where the KJV has “the pure in heart.” The word “all” is the only change. This is a minor change, and simply adds in a word that fulfils the implicit meaning already present in the text. This type of change could as easily have been a slip of the tongue as a purposeful addition.