The Book of Mormon (and all of scripture) uses the word “joy” in a variety of contexts. Mosiah 4:3 describes one aspect of joy that I think has a very specific meaning and application. A little background: King Benjamin has spent the last several chapters teaching his people in a beautiful “farewell address” before his turns the kingship over to his son, Mosiah II. Benjamin is considered a prophet-king. He is a righteous man, he has received instruction from divine visitors, and he is filled with charity––he desires the salvation of his people so he teaches them the Plan of Salvation and prophesies of Jesus Christ. In relating to the people what would happen to their souls if left untreated in a state of sinfulness, King Benjamin paints a miserable picture. The people feel the weight of an eternity of damnation (i.e. not living forever in the presence of God). But he tells them of Jesus Christ, the Son of God, who will come to earth in several hundred years to suffer and die for the sins of every person. No one has to suffer an eternal damnation because Jesus Christ will make it possible for them to repent, become clean from their sins, and qualify for eternal life. The people cry out, “O have mercy, and apply the atoning blood of Christ that we may receive forgiveness of our sins, and our hearts may be purified; for we believe in Jesus Christ, the Son of God…” (v. 2).
“And it came to pass that after they had spoken these words the Spirit of the Lord came upon them, and they were filled with joy, having received a remission of their sins…” (v. 3). “Joy” here indicates a special kind of happiness, more than happiness, that can only be achieved through faith in Jesus Christ, repentance, and forgiveness of sin. It is a taste of what we can experience in the Celestial Kingdom, living with God and our qualifying family members. This particular use of joy, so clear here in Mosiah 4:3, helps us understand the use of the word “joy” elsewhere in scripture. True joy can only be achieved through the remission of sins.