I once heard a story about a doctor who visited his patients each morning as they were lying in their beds in the hospital.
Every morning the doctor would greet his patients with the same words; ‘Good morning, how are you?’ he would say. But every morning he would follow this greeting with the same requests; ‘Please show me your tongue.’
It was noticeable that the doctor paid little attention to the answer to the patients response to his first question, ‘how are you?’
The patients could only give a rough estimate of what they felt their condition was. But when the patient stuck his tongue out, the doctor paid a lot of attention to it. Each morning the doctor would base his assessment of the patient’s condition, not on what they thought, but on what he could see from the condition of their tongue. The bible would lead us to believe something similar: God doesn’t base his assessment of our condition on our rough estimate of who we think we are, He bases His assessment on His analysis of our tongue! Our tongues are a much better guide to our spiritual condition, than our own self-estimate.
There are many passages within Scripture that establish a clear connection between the heart and the mouth. For example, Jesus says in Matthew 12:33-37: ‘Make a good tree and its fruit will be good, or make a tree bad and its fruit will be bad, for a tree is recognized by its fruit. You brood of vipers, how can you who are evil say anything good? For out of the overflow of the heart the mouth speaks. The good man brings good things out of the good stored up in him, and the evil man brings evil things out of the evil stored up in him. But I tell you that men will have to give account on the day of judgment for every careless word they have spoken. For by your words you will be acquitted, and by your words you will be condemned.’
Jesus establishes a direct connection between the mouth and the heart. He refers to the heart as the tree and to the words that come out of the mouth as the fruit. He says, for instance, ‘The good man brings good things out of the good stored up in him, and the evil man brings evil things out of the evil stored up in him’. You will notice Jesus uses the word ‘good’ three times, and he uses the word ‘evil’ three times. If the heart is good, then out of the mouth will come words that are good. But if the heart is evil, then out of the mouth will come words that are evil.
In Matthew 7:17-18, Jesus explains: ‘Likewise every good tree bears good fruit, but a bad tree bears bad fruit. A good tree cannot bear bad fruit, and a bad tree cannot bear good fruit.’
Jesus makes it clear that the nature of the tree determines the kind of fruit it produces. This also means that when we see the kind of fruit a tree produces, we can see the nature of the tree.
The tree is the heart and the fruit is the mouth. If the heart is good, the words that come from the mouth will be good. But if the words that come from that mouth are evil, we know that the heart is evil. You cannot have bad fruit come from a good tree and neither can you have good fruit come from a bad tree. There is a clear connection here between the state of the heart and the state of the mouth.
We may deceive ourselves about the state of our hearts with all sorts of ideas about our own goodness, purity or righteousness, but the sure and unfailing indicator is what comes out of our mouths. If that which comes out of our mouths is corrupt, then it is a clear sign that our hearts are corrupt. The voice tells with words what the condition is of our heart.
This is what Jesus meant when he said, ‘A good tree cannot bear bad fruit, and a bad tree cannot bear good fruit.’ Like the doctor attending to his patients, when we give God a rough estimate of our spiritual condition He listens with only one ear – Instead, God says, ‘Show me your tongue – This is what I really want to look at, because this will reveal the true condition of your heart!’