Your Mouth and Behavior Reveal Your Heart

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Jesus tells us in today’s Bible reading* that what you say and do reveal your heart.

The Bible tells us that all of us have sinned and fallen short of God’s glory. Our sin brings about death and separation from God. (Romans 3:23, 6:23; Ephesians 2:1-3)

Jesus tells us here that our problem isn’t our words and our behavior. Our problem is our hearts! Your words and behavior reveal your heart. Jeremiah tells us the same thing.

The heart is more deceitful than anything else, and incurable—who can understand it?
Jeremiah 17:9 (CSB)


We often think of the problem of sin as the individual sins that we commit either by commission (things we do, but shouldn’t do) or omission (things we should do, but don’t). We tend to think that sin is limited to words and behavior.

Because we base our understanding of sin on our words and behavior, we communicate to people (family, friends, coworkers, and even ourselves) that if they will just change the words we say or their behavior — clean up our language, stop doing certain things, and start doing certain things — God will be happy with us. By doing so, we are communicating a dangerous heresy: legalism.

We see legalism throughout Jesus’ ministry as He deals with the Jewish leaders of His day. Whenever He encounters it, He points out that they are straining at gnats and swallowing camels. (Matthew 23:23) We would say that they were missing the forest for the trees.

The Jewish leaders in Jesus’ day lived exemplary lives. Their behavior was impeccable. To avoid individual sins, the Jewish leaders invented additional laws to supplement the Mosaic Law. For instance, to prevent “traveling” on the Sabbath, they determined how far you could walk without “traveling” (about 2000 cubits or .6 miles). We see this described as “a Sabbath day’s journey”. (Acts 1:12)

One of the things that upset the Jewish leaders is that Jesus healed on the Sabbath. But He reminded them, “Which of you whose son or ox falls into a well, will not immediately pull him out on the Sabbath day?” (Luke 14:5 (CSB)

Instead of looking at words and behavior as the source of our sin problem, Jesus says,

“What comes out of a person is what defiles him. For from within, out of people’s hearts, come evil thoughts, sexual immoralities, thefts, murders, adulteries, greed, evil actions, deceit, self-indulgence, envy, slander, pride, and foolishness. All these evil things come from within and defile a person.”
Mark 7:20–23 (CSB)

This month we celebrate the Reformation. The heart of the Reformation was the question Martin Luther struggled with: How can a person have a right standing before God? How can a person be accepted by God?

Like the Jewish leaders of Jesus’ day, your words and behavior may be exemplary. You may feel pretty good about your standing before God, based on your words and behavior. But your sin problem isn’t your words and behavior. Your sin problem is your defiled heart.

If cleaning up our words and behavior were all that was necessary for us to have a right standing before God, then Jesus didn’t have to suffer and die! If cleaning up our words and behavior were all that was needed for us to have a right standing before God, then Jesus didn’t even need to come to earth!

By telling ourselves and other people that we just need to clean up their words and behavior we’re telling ourselves — and God — that Jesus’ sacrifice wasn’t necessary!

But Jesus’ sacrifice was necessary! Jesus’ death was necessary for solving our sin problem! Our sin problem is much deeper than what we say and what we do or don’t do. Our sin problem is a heart problem.

Words and behavior are the fruit that grows from the root of sin in our hearts. Your words and behavior reveal your heart. Cleaning up your words and behavior is like pruning leaves and branches from a tree. Instead, you really need to chop down the entire tree and dig up the root!

What you say and what you do (or don’t do) reveal your heart.
You have to deal with the root, not just the fruit.

* Chapters covered in today’s reading:
Matthew 15
Mark 7
Mark 8:1-10

This devotional was originally published on October 18, 2021.

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