Over the past two years, I have become a huge fan of television crime shows. I watch CSI, Law & Order, Cold Case, and Numbers, of course, all of which are fictional. But I enjoy “true crime” shows the most. My wife and I TiVo every episode of American Justice and Cold Case Files. What fascinates me about these shows is the way detectives patiently gather and sift evidence in order to solve the case and convict a criminal.

Mark 8.1–21 tells two stories. The first is the feeding of the 4000 (vv. 1–13). The second reports on the debriefing meeting Jesus held with his disciples after the event. The Pharisees play a negative role in both stories. In the first, they refuse to let the evidence of Jesus’ power convince them that God has sent him. In the second, Jesus warns the disciples not to become like them. Let’s take a closer look at both stories.

The Gospel of Mark is filled with stories about Jesus’ miraculous powers. In our day, people think of Jesus primarily as a teacher. In Jesus’ day, people thought of him as a teacher, exorcist, and miracle worker. He both taught about and demonstrated the power of the kingdom of God. When the Pharisees witnessed Jesus feed the 4000 with seven loaves of bread, they had already seen or heard about his many other miracles, including the feeding of the 5000, which is recorded in Mark 6.30–44.

The Pharisees’ knowledge of Jesus’ miracles is what makes their request in verse 11 so aggravating. “To test him,” Mark says, “they asked him for a sign from heaven.” Jesus responded: “Why does this generation ask for a miraculous sign? I tell you the truth, no sign will be given it.” Of course, Jesus had already given them many “signs from heaven—exorcisms, healings, a resurrection, and two miraculous feedings of multitudes. The Pharisees simply refused to look at those. They wanted yet another. They are like the defense attorneys in my crime shows who, faced with a mountain of evidence against their client, think there is still a reasonable shadow of a doubt.

And that brings us to the disciples. Jesus warned them about “the yeast of the Pharisees.” This is a colorful way of talking about the Pharisees’ skepticism, which will—like yeast—spread throughout the believing community if unchecked by faith. But faith is not unreasonable. Jesus provides evidence that faith in him is well placed. He cites the feeding of the 5000 and of the 4000 as evidence in his favor. “Do you still not understand?” he asks the disciples. In other words, will you believe in me because of what you have seen with your own eyes?

There comes a point in our lives when we must make a decision about Jesus. I know people who put off that decision, also seeking more data, more evidence, more arguments in Christ’s favor. I’m always happy to give such people what they’re asking for—since there is plenty of evidence for Jesus. But at some point, we all have to make up our minds about Jesus. Asking for more evidence may be an indication of legitimate spiritual seeking. But it also may be an indicator of illegitimate, obstinate, unreasonable doubt.