Here is the positive part of the promise. Moroni begins with the penalty associated with the promise (verse 10) because he is most painfully familiar with that consequence. He does not forget, however, that there is a positive aspect to the covenant associated with the land. It is very clear that this is the promise of the land as understood by Moroni, as he specifically notes that Jesus Christ is the “God of the land.”
In Nephite theology, there is a very clear association between Jehovah and the Messiah who came and is to come. That Jehovah/Messiah/Jesus are all the same person. Even though they understand the difference between God the Father and Jesus Christ as Son after Christ’s appearance in the New World, yet they understand Jesus in his Messianic role. The nature of the appearance of the Savior in the New World allowed them to see Jesus in that larger sense more readily than did those of the Old World, who might have seen him only as his human aspect (as some still do).
Literary: Moroni places both aspects of the promise in similar structures.
Verse 10 begins: For behold, this ls a land which is choice above all other lands:
This verse begins: Behold, this is a choice land
This is an intentional paralleling of the essential promise as a prelude to the specific clause of the promise.