There's no doubt you've heard of it, but let's dig deep.
The word "prodigal" is an adjective that means wasteful or spendthrift or wanton (sorry, the SAT is coming up). Luke doesn't actually call his character the "prodigal son," but we modern peeps just love us some titles.
Here's a quick recap: a father gives his two sons their inheritance. One of them takes his newly found fortune to a far-away country and spends every single dime living it up. But there's a severe famine, and the son is forced to tend pigs, which are unclean animals for Jews—kind of double blow to this son who's already sunk pretty low. Eventually, the son decides to return to his father, who is overjoyed to see him and welcomes him home with a big party.
Meanwhile, the second son, who's been at home working hard for his father this whole time, is kind of perturbed at all of this hullabaloo. His father's never thrown a big party for him and here this brother of his is feasting on the juiciest steaks after squandering all of his inheritance on liquor and prostitutes. How is that fair?
The father's response resounds with intense humanity: "Son, you are always with me, and all that is mine is yours. But we had to celebrate and rejoice, because this brother of yours was dead and has come to life; he was lost and has been found" (15:31-32).
The story of the Prodigal Son is only found in Luke (15:11-32)—none of the other gospels give it a go. And it's not surprising, because the parable picks up several important Lukan themes. Let's take a look.
Jesus tells the story in response to scribes and Pharisees who are "murmuring" or "grumbling" because Jesus welcomes and even eats with the "tax collectors and sinners" who are coming out in droves to listen to his teaching (15:1-2). Hanging with the wrong crowd is a common criticism of Jesus (5:29-32; 7:37-39; 19:7), who repeatedly insists that he has come precisely for such "sinners" as well as other social outcasts.
As a way of explaining the logic of this mission, Jesus tells two little parables right before he launches into the story of the prodigal son. In one, a shepherd leaves ninety-nine sheep in order to search for "the one that is lost" and rejoices when he finds it (15:3-7). In another, a woman searches her whole house for a single lost coin and when she finds it, she throws a party for her friends (15:8-10). Jesus explains that this is the joy the otherworldly beings feel when a single person who's in really bad shape turns his or her life around (15:7, 10).
Now think back to the prodigal son. You can probably see why his father throws a big party for him after he gets back. Luke insists that "sins" or past errors or crimes may by erased by "forgiveness," a central feature of Jesus's work at several important junctures (4:18; 5:20; 7:48).
The brother's response to all of this is also worth checking out, especially in terms of Luke's attempt to come to terms with the negative response of the Jewish leaders to Jesus in general.
Like the Jewish leaders, the brother claims to have been faithful to his father's every "command" (15:29) and is pretty resentful of the prodigal son's second chance; sounds like the Jewish leaders in 5:29-32, 7:37-39, 15:1, and 19:7, right? But the brother's concern is voiced sympathetically here (15:28-32), and the father levels honestly—even tenderly—with his faithful son. Does that mean the grumbling of Jewish leaders also has substance? Will they join the Jesus party? Will the other brother?
Everyone loves a second chance, right? That might just be why this particular parable has such staying power.