He actually answers that question Himself, or gives one answer to it, when He tells the parable of the sower and the soils and His disciples don’t get it. They come to Him and say, “What was that all about?” and He explains it to them.
He says, “I’m giving these explanations to you because you’re my disciples. But one of the reasons I tell these parables is because when I tell the parables it actually makes clear whether people really grasp the meaning of the kingdom or not” (see Matt. 13:11-17, Mark 4:10-12, or Luke 8:9-10).
I don’t know if it’s said so often these days, but there was a time when people constantly said to ministers, “You should tell more stories like Jesus so that we can understand.” But Jesus didn’t tell these parables so much so that people would understand. They were really test cases of whether they understood the gospel that He preached in other words. When you think about it, that’s the case.
Think about the parable of the Pharisee and the tax collector (Luke 18:9-14). We all know what the answer is to the question “Which man went down justified?” but that’s only because we don’t really grasp the parable. Nobody listening to Jesus thought it would be the tax collector who went away from the temple justified.
I sometimes say to people, “Just think about these two men. You’re an evangelical Christian. Which of these two are you more like? Don’t you say to God, ‘I thank you that I’m not like other men’; ‘I thank you that you’ve helped me to discipline my life’; ‘I thank you that you’ve helped me to give away money rather than hoard money’? When you begin to think of those things, actually you sound more like the Pharisee.” And that’s very, very uncomfortable: to discover that, even though you trust in Christ, there’s a Pharisee deep down inside you.
Jesus tells these parables to probe inside us to see whether we really understand the gospel and whether the gospel is really beginning to transform our lives.
They’re not just stories. They’re weapons in spiritual warfare.