The most common interpretation of the Biblical parable of the prodigal son is that the illustration represents God's desire to forgive sinners who demonstrate repentance. The epilogue emphasizes the parable's primary meaning by describing the negative attitude of religious leaders towards sinners at the time.
The parable starts with the prodigal son asking his father for his share of the inheritance. Although this was an uncommon request at the time, the father agrees and lets him leave the home. Many interpret the parable's introduction as a representation of the free will that God gives to his people. The prodigal son spends his inheritance recklessly and eventually succumbs to hunger and poverty. Bible readers interpret this part as a demonstration of the painful consequences of using free will improperly or sinfully.
The prodigal son realizes that he was wrong to leave the household early and decides to return. The son begs the father for forgiveness and submits to potential servitude. Many interpret this as the type of repentance that God expects from returning sinners. The father refuses to make the son a servant and accepts him back unconditionally, showing God's eagerness to accept returning sinners who have shown remorse for their actions.
The prodigal son's older brother is angry when he sees that his younger brother is receiving more attention. The father asks what is bothering the older brother, who responds that his father is rewarding his younger brother for having left. Given the context of Jesus' parable, this older brother probably represents the Pharisees and their attitude toward Jesus' love for sinners. The parable ends with the father's expression of joy over his son's return, further emphasizing God's happiness upon forgiving someone.