Agalliasis is the Greek word that is used to describe great joy in five places in the Bible.
First, in Luke 1:14, the angel tells Zechariah that his son John (the Baptist) would be a great joy to him. Certainly, because Zechariah and Elizabeth did not have any children, this was true.
Second, in Luke 1:44, John “leaps” with exuberant joy in Elizabeth’s womb when Elizabeth meets Mary. It was an extreme happiness that the Messiah was coming.
Third, in the church in Acts 2, the people ate bread with one another in their homes with exhilarating joy. They were exceedingly glad to be together, a spiritual family who share with one another the good news.
Fourth, Jesus is described in Hebrews 1:9 as being anointed with the oil of extreme joy. In some translations, he is said to have been given more joy than anyone else. The connotation is a king who is anointed with oil upon his royal appointment.
Finally, it says in Jude 1:24, “To him who is able to keep you from stumbling and to present you before his glorious presence without fault and with great joy.”
Who has great joy in this verse, us or God? Probably both! But in summarizing, it seems that this word is used for a special kind of joy when something new is being experienced. Zechariah will be joyful when he finally has a child. John is joyful because the Messiah is finally coming into the world. The new disciples are joyful because they are following a new way of hope, with new brothers and sisters. Jesus is joyful because he is instituting a spiritual kingdom. And we will be joyful when we finally enter heaven and can be in the Most Holy God’s presence. God will be joyful when we are finally home, in His arms.