This verse is part of the Parable of the Lost Sheep, one of Jesus' parables about God's love for sinners and his desire for their salvation. In this parable, a shepherd leaves his 99 sheep to go in search of the one that has gone astray. Jesus is using this story to illustrate God's love for sinners and how he rejoices when a sinner repents and returns to him.
The "joy before the angels of God" refers to the joy that is experienced in heaven when a sinner repents and turns to God. The verse highlights the significance of repentance and the joy it brings to God and the angels in heaven.
The parable of the Lost Sheep is one of three parables in Luke 15 that deal with the subject of lost things being found (the other two are the Parable of the Lost Coin and the Parable of the Prodigal Son). These parables illustrate the compassion and mercy of God towards sinners, and the joy that is experienced in heaven when a sinner repents and returns to God.
In each of these parables, the central figure goes out of their way to seek out what is lost and bring it back to its proper place. In the case of the Lost Sheep, the shepherd leaves his 99 sheep to go in search of the one that has gone astray. In the Parable of the Lost Coin, a woman lights a lamp and searches carefully for a lost coin. And in the Parable of the Prodigal Son, the father runs to welcome back his son who has returned from a life of sin.
Each of these parables conveys the message that God values each person and is willing to go to great lengths to seek them out and bring them back to a right relationship with him. The "joy before the angels of God" mentioned in Luke 15:10 represents the happiness and delight that God experiences when a sinner repents and turns to him.
In summary, the Parable of the Lost Sheep and the related parables in Luke 15 illustrate the love and compassion of God towards sinners, and the joy that is experienced in heaven when a sinner repents and returns to God. These parables emphasize the value that God places on each person and his willingness to seek them out and bring them back to a right relationship with him.
Luke 15:10. I tell you, there is joy in the presence of the angels of God over one sinner repenting.