Luke 15:1-2 gives us the reason the following parables were told to the Pharisees.
Rather than rejoicing at sinners coming to the Lord, they scoffed.
So Jesus reminded them how they should be acting.
The 3 parables:
Lost sheep returned - should be a time to rejoice! (Luke 15:6)
Lost coin returned - should be a time to rejoice! (Luke 15:9)
Lost brother returned - should be a time to rejoice! (Luke 15:32)