Sermon session

Heart Monitor

Session #089 Heart Monitor

Scripture Matthew 12:33-37

Summary Matthew 12:33-37 is a continuation of Jesus’ response to the Pharisees’ opposition against Him. By exposing their words, Jesus exposed the true intent and condition of their hearts. The principle: to monitor the heart, check the mouth. How is your heart doing? What would your words and manner of speech reveal?


“Either make the tree good and its fruit good, or else make the tree bad and its fruit bad; for a tree is known by its fruit. Brood of vipers! How can you, being evil, speak good things? For out of the abundance of the heart the mouth speaks. A good man out of the good treasure of his heart brings forth good things, and an evil man out of the evil treasure brings forth evil things. But I say to you that for every idle word men may speak, they will give account of it in the day of judgment. For by your words you will be justified, and by your words you will be condemned.” Matthew 12:33-37

These verses are a continuation of Jesus’ response to the Pharisee’s opposition against Him. The previous teaching touched on Jesus’ warning of the ‘Point of No Return: Blasphemy against the Holy Spirit’. Here, Jesus pointed out that the true intent and condition of their hearts are revealed by their words. The principle shared in this teaching is that we monitor our hearts by checking our mouths.

Trees and Fruit

Jesus first used the imagery of a tree and its fruits to make a strong point in Matthew 7:15-20 where He warned His disciples about false prophets that “you will know them by their fruits.” In Matthew 12:33-37, the warning is directed at the Pharisees and also a general warning to everyone. Like a good or bad tree bears good or bad fruits respectively, our words reveal what is in our hearts (Matthew 15:18-19). This teaching is an alignment check to monitor the heart by checking the mouth as “out of the abundance of the heart the mouth speaks.”

A Case Study of the Pharisees

The Pharisees are a post-exilic religious sect, who wanted to stay true to the law, promote righteousness and uphold holiness. Over time, they became scholars, lawyers and teachers in the Law. Their heart was to help the people not break the Law by putting in more cautionary prohibitions as fencing. This did help the people to ‘keep’ the Law but missed the heart of what the Law was about. They were known for their oral tradition and their words became the default interpretation of the Law, and later became more important than the Law. However, though they are portrayed as Jesus’ antagonists, not all Pharisees were bad e.g., Nicodemus. Possibly only a small group gave the Pharisees a negative label. Jesus was not against the Pharisees as He loved all and desired all to be saved. He was against a pharisaical heart i.e. an evil heart that is self-seeking for position, prestige, and power; a heart that is greedy and covetous, lovers of money (Luke 16:14); hardened and prideful hearts, hearts of unbelief. Anyone, not just the Pharisees, can fall into this category.

Jesus also called the Pharisees a brood of vipers as their double-talk is like the forked tongue of a serpent, outwardly righteous with flowery prayers and spiritual talk but inwardly defiled as they do not mean what they say nor do they live it. In Matthew 12:35, Jesus said, “a good man out of the good treasure of his heart brings forth good things…” The Greek word for treasure is ‘thesauros’ where we get the word ‘thesaurus’, which means a treasury of words. If you are a good person, then you will have a treasury of good words while an evil person will have a treasury of evil words. Further ‘bring forth’ in Greek is ‘ekballo’ which also means to throw up or gush out. Therefore, out of a good heart, good words and actions will gush out and overflow, and out of an evil heart, the evil words will gush forth without control. An evil person may say good things but does not mean it. Inherently the evil will be revealed under pressure or stress e.g. when threatened by Jesus, the Pharisees’ words began to reveal who they really were. We also find that everyone is nice until we have to work with them. On the contrary, if you have a good heart, you will find it hard to say evil things and even if words were spoken for discipline and correction, it will be spoken with love and grace, for the good of the other person. James mentioned the same principle of blessing and cursing using the imagery of spring water and a fig tree (James 3:10-12).

In Matthew 12:36, Jesus said that men will give account in the day of judgment for every ‘idle word’ they may speak as the Pharisees were saying a lot of useless words against the kingdom. The Greek word for ‘idle’ is ‘argon’ meaning no work (a lot of talk and no action or hypocrisy) or negative work (words or work that are against the kingdom). Idle words will reveal an idle heart as words express the convictions (beliefs) in our hearts and action and assignments will flow out of these convictions.

How is one justified by word or works? In Romans 3:20, Paul pointed out that there is no way anyone can keep the law perfectly, or do anything perfectly in the sight of God. As such, all are already condemned and in need of salvation through Jesus Christ by the Holy Spirit (John 3:16-21). “A man is not justified by the works of the law but by faith in Jesus Christ” (Galatians 2:16). Hence, Jesus is warning the Pharisees that they do not keep the law to be saved. He saved them that they could keep the law perfectly by relying on the Holy Spirit; and not reject and blaspheme against Him, revealing their hearts and coming really close to the point of no return. This warning is not just for the Pharisees. Every heart without Jesus is a pharisaical and evil heart in need of salvation. We can see that by listening to the way people talk. Therefore we need to monitor our heart by checking our mouth.

Inherently, as all our hearts are evil, we are bad trees that yield bad fruit. We need to make the tree good so that it will yield good fruit. It is not about trying to say nice things or being polite but having a complete overhaul from the inside out i.e. we need new hearts. This will only happen when we are born again for God replaces the heart of stone with a heart of flesh, with the law written upon these new hearts, and the new hearts will produce new fruits and good words that are led by the Holy Spirit (Ezekiel 36:26-27, Jeremiah 31:33-34).

Evidence of New Hearts

As believers of Christ, we have new hearts and the principle is that we monitor our heart by checking our mouth. Here, we will go through an alignment checklist that will set us on the right track by totally relying on the Holy Spirit.

First, we consider some overarching principles. Are we speaking words of life (John 6:63 and 68) – of faith, joy, hope that points us to the eternal life that we have and not words of fear, hopelessness, and death? Are we exhibiting the fruit of the Spirit: love, joy, peace, longsuffering, kindness, goodness, faith, gentleness, and self-control? (Galatians 5:22-23) How does our speech fare in each of these categories? As believers, do we honour and bless everyone, not only those who are nice to us? (1 Peter 2:17 and 3:9)

Next, how do we sound to the world? We are to “walk in wisdom towards those who are outside, redeeming the time. Let our speech always be with grace, seasoned with salt, that we may know how we ought to answer each one” (Colossians 4:6).

Within the body of Christ, how should we speak to one another? We are to “speak the truth in love” (Ephesians 4:15) and give proper feedback but not gossip, carry tales, slander, or sow discord amongst brethren (Proverbs 6:19b). “God hates a lying tongue” and those who give false witness (Proverbs 6:17 and 19a). We are to build one another in love and grace with words for necessary edification; put away all bitterness and malice and be kind and tenderhearted, forgiving one another as God in Christ has forgiven us (Ephesians 4:29-32).

We are to rejoice always, giving thanks always for all things to God, continually offering the sacrifice of praise to God (Ephesians 5:19-20, 1 Thessalonians 5:16-18, Hebrews 13:15). We are also to do all things without murmuring and complaining as the world does (Philippians 2:14-15). Instead of complaining against leaders, we should be praying for them and giving constructive feedback.

For leaders at every level (including parents), we should avoid foolish, ignorant disputes that generate strife, and shun profane and idle babblings. We need to be gentle and patient, handling opposition with humility instead of being quarrelsome. We should preach the Word to convince, rebuke and exhort. Leaders need to be good examples. It is easy to teach and difficult to live out what is taught.

The evidence of a new heart seemed impossible for man, to talk and live as described above (James 3:8), but with God all things are possible. Only the Holy Spirit can make the tree good, give us a new heart to enable us to renew our mind so that we are transformed.


In conclusion, how is your heart? To monitor the heart, check the mouth. So listen to your heart by listening to your words as our hearts are desperately deceptive. Our words will give us the right indicators and signs of where our hearts really are. May we not have idle words that amount to nothing or work against the things of the kingdom. May we have kingdom hearts that will speak kingdom words that will reveal themselves in kingdom work. If you have a pharisaical heart, this is the time to repent. If you are still struggling with your words and works, ask the Holy Spirit to help and enable us to be a blessing to others.