What does Luke 15:3 mean?

The Pharisees are condemning Jesus' choice to associate willingly and warmly with immoral, socially outcast people (Luke 15:1–2). This is not new for Jesus (Luke 5:27–32; 7:36–39). The Pharisees are afraid of becoming ceremonially unclean if they interact with sinners (Mark 7:1–4), not to mention the damage to their reputation. Jesus has explained that He associates with sinners to draw them to repentance. He is not endorsing sin, but offering forgiveness, so they can be restored to relationship with God: "I have not come to call the righteous but sinners to repentance" (Luke 5:32).

In response to this latest critique, Jesus gives three parables. This is also characteristic to Jesus' interactions with Pharisees. Parables are extended metaphors set on earth that represent a spiritual truth. They're also a kind of code. Only people who trust Jesus enough to ask can accept their spiritual meaning. The rest of the audience, which often includes the Pharisees, usually don't understand what Jesus is really saying. As He told the disciples, "To you it has been given to know the secrets of the kingdom of God, but for others they are in parables, so that 'seeing they may not see, and hearing they may not understand'" (Luke 8:10). If audience members don't want to know what Jesus is talking about, He makes it easy for them to remain in their ignorance.

The three parables represent three different ways a person can pull away from God and how God responds to each. The parable of the lost sheep shows how willing God is to pursue someone who abandons Him because of their foolishness. The parable of the lost coin talks about someone who doesn't even know they've left God. The parable of the prodigal son shows how God waits patiently for those who deliberately rebel against Him to come home so He can restore them with His love.