Luke 15 is Jesus’s response to Pharisaical grumbling (v.2). The entire chapter is a response in parable form. It’s one parable with three different episodes. It’s his explanation for why he “receives sinners and eats with them” (v.1). There’s the parable of the lost sheep, the parable of the lost coin, and the parable of the lost son. Both sons are lost in different ways. What the religious leaders meant as derogatory and a character assassination is actually good news! The actions of the shepherd, woman, and father become illustrations for what God is doing through his son — Luke 19:10 “For the Son of Man came to seek and to save the lost.” The mission of seeking and saving the lost is so wonderful that twice tells us to rejoice, "for there will be more joy in heaven over one sinner who repents" (vv.6-7, 9-10).
Here’s the reality —“All we like sheep have gone astray; we have turned—every one—to his own way; and the LORD has laid on him the iniquity of us all” (Isaiah 53:6). Who is Isaiah talking about? Jesus Christ (Messiah). He alone is the answer to our lostness. Jesus said, “I am the good shepherd. The good shepherd lays down his life for the sheep” (John 10:11). As the Good Shepherd he allowed himself to also be a sacrificial lamb. John states the necessity for this in John 1:29 “Behold, the Lamb of God, who takes away the sin of the world!” This is the gospel — the “good news!!!”