These verses give us a detailed account of the conversion of Alma, son of Alma (whom we often call Alma the Younger), and his friends, the four sons of King Mosiah (another account is given in Alma 36). These young men are characterized as “very wicked” and “idolatrous”; “they were the very vilest of sinners” (Mosiah 28:4).
We do not have a catalog of all their crimes and sins, but in modern terms any one of these young men might be portrayed something like this: He does illegal things, violating the laws of the land (for example, experimenting with and becoming addicted to illicit substances); he does immoral things, violating the laws of God (including using pornography and fathering children outside the bonds of marriage); he lies to his parents; he cannot be trusted; he steals things from his parents and siblings to support his evil habits; he seeks out the wrong kind of friends and takes others down with him; he refuses to work, sleeping during the day and drinking and partying at night, living in a world of darkness, where everything is secretive—he is always vague about where he is, who he is with, and what he is doing; he denies and rejects God and makes light of the things of God.