We see the happenings of Alma 4 even today. We have scripture telling us what not to do, yet we still do. The warnings have been given, the prophesy has been told. The fulfillment will happen and we will each answer for our own wickedness or righteousness upon the earth come judgement day.
This isn’t a very long chapter to begin with, but to make a short story even shorter: The Nephites originally believed that they lost all of their families in battle due to their transgressions and many people turned their hearts to God. Over the course of the next year though, many people began to be puffed up in pride because they were thriving as a people. These people stopped following basic kindness rules and helping the needy and the poor which eventually lead to them being wicked. Alma decided that he needed to act. Alma chose a righteous man named Nephihah and he delivered up the chief judge position to him and kept the high priest seat to himself. Alma then began to go out to the people to bear his testimony and turn the hearts of the people back to Heavenly Father. Alma believed that these actions were going to be the only way to save the Nephites from utter annihilation.
And I leave this with you in the name of Jesus Christ, Amen.