These three verses are all the same concept. Jarom is discussing the role and effect of the prophets on the people of Nephi. It is interesting that he should say that they "threatened" the people. He is indicating the clarity with which they preached the consequences of falling away from the way of the Lord. The conditional promise was theirs, but only upon the condition of righteousness. The prophets kept that realization before the people, and by doing so, the people kept the law.
Victor L. Ludlow takes particular note of a phrase in verse 11:
"Jarom also recorded an interesting teaching technique of the prophets in verse 11. He said that the prophets and other spiritual teachers of the people taught them to believe in the coming Messiah "as though he already was." This mental association of anticipating something in the future as though it were already present helped the people remember their weaknesses and repent of their sins at that time. Thus further punishments from God were avoided. (Verse 12.) If society today could anticipate Christ's second coming and the reality of the judgment day and resurrection as though they were all happening now, perhaps more people would return to the gospel paths and avoid further divine punishments." (Ludlow, Victor L. "Scribes and Scriptures." In: Studies in Scripture volume 7: 1 Nephi to Alma 29. Provo, Deseret Book. 1987, p. 200).