In the parables of the Lost Sheep, the Lost Coin, and the Lost Son of Luke 15, the theme of joy is repeated. In Luke 15:7, and 10 Jesus said, "Joy shall be in heaven over one repenting sinner."
In the third parable of the series, the older brother complained about the father's incredibly generous reception of his prodigal son. When the father defended himself to the older brother, he said, "It was necessary to be jubilant and be glad." God rejoices over reestablished relationships. The Fall and our own choices kept us from a relationship to God, but now that it is reestablished heaven rejoices.
Heaven is Heaven because of the quality of affection and delight of Heaven's God. Heaven looks forward to meeting us and is thrilled when we come in from the darkness into the light of God where we can meet the smiling face of God. Heaven's most careful and closest observers, the angels, find great joy in watching the wondrous smile on God's face over the one sinner who chooses God and finds a relationship with Him.
