5 For he put down all the priests that had been consecrated by his father, and consecrated new ones in their stead, such as were lifted up in the pride of their hearts.
6 Yea, and thus they were supported in their laziness, and in their idolatry, and in their whoredoms, by the taxes which king Noah had put upon his people; thus did the people labor exceedingly to support iniquity.
7 Yea, and they also became idolatrous, because they were deceived by the vain and flattering words of the king and priests; for they did speak flattering things unto them.
One truth illustrated again and again in the Book of Mormon is how quickly one wicked leader can lead his people into wickedness. The people who came and settled in the land of Lehi-Nephi were righteous followers of King Benjamin who had left to escape destruction at the hand of God. And yet, within no more than a generation they were led into idolatry, winebibbing and hatred towards a prophet of God.
Truly, the example of those that we look up to and admire sets the tone for the nation. This is part of why we are commanded to vote for wise and good leaders, not just leaders with whom we agree. When we elect idolatrous men who forget God, the moral values of the nation decay and we collectively find it harder to remember God. Adulterous and lazy leaders aspire those qualities in the nation.
On the other hand, righteous leaders like Moroni can galvanize and inspire the nations towards God and righteousness. This revival can also occur in a relatively short period of time.