Jesus is incredibly clear in his warning of Matthew 12:36–37: “I tell you, on the day of judgment people will give account for every careless word they speak, for by your words you will be justified, and by your words you will be condemned.” Even our careless words will be judged! That ought to make us pause. This means that the words we speak publicly and privately, carefully, intentionally, or even without thought, will all be judged. 

One of the reasons I absolutely love expository preaching and insist that pastors preach verse-by-verse through books of the Bible for their congregations is because the Word of God is always timely. Rather than preaching hobby-horses or tired and trite topics of interest, expository preaching, when done well, forces the pastor to faithfully handle the texts of Scripture as they come down the pipeline. There’s no guessing about what’s coming next Sunday for the congregation, either. They can rest in the assurance that—Lord-willing—the preaching will pick up in the text where it left off the previous Sunday.

Some, however, worry that expository preaching prevents pastors from engaging with pressing topics of the times. This, however, is hardly ever the case. Our sovereign God has a peculiar way of lining our preaching texts up with pressing events in often unexpected ways.

This was my experience very recently as I have been preaching through the Gospel of Matthew for nearly a year-and-a-half. Recently, there has been some talk about the use of vulgar language by certain evangelicals, and some in our congregation (and some friends outside of our congregation, too), have been asking me about how Christians should understand the use of language. As the Lord would have it, amid these questions, Matthew 12:33–37 lined up as my next sermon, and perfectly answered many of these questions. Below, I will share some highlights from this sermon about Christian speech.

Your Actions and Words Are the Fruit That Reveal Where You Are Rooted

Jesus makes the issue clear. Those who are in Christ ought to speak and act in a righteous way, because, as he plainly states in Matthew 12:33, “Either make the tree good and its fruit good, or make the tree bad and its fruit bad, for the tree is known by its fruit.”

Jesus uses the metaphor of the tree and its fruit on more than one occasion and it’s incredibly simple to understand. If I’m a branch on an apple tree, what kind of fruit will I bear? Apples. No one expects to find oranges on an apple tree because a tree will always bear fruit corresponding to the type of tree it is. If an apple tree bears oranges, something has gone horribly askew. It simply isn’t possible. It is, ultimately, against the nature of the branches to bear fruit differing from the rest of the tree.

So it is with people. If we’re saved and rooted in Christ, we’ll be marked by holy speech and righteous deeds. If we’re lost and chained to sin, we’ll be marked by evil speech and wicked deeds. Thus, Jesus said, “Abide in me, and I in you. As the branch cannot bear fruit by itself, unless it abides in the vine, neither can you, unless you abide in me. I am the vine; you are the branches. Whoever abides in me and I in him, he it is that bears much fruit, for apart from me you can do nothing” (John 15:4–5).

While we know we are not saved by our works, but by faith in Christ alone, yet it is true that a Christian is known by their speech and actions. Hence, there are evidences of salvation, and our speech is one major evidence of whether or not we’re saved and indwelled by the Holy Spirit.

What Fills the Heart Moves the Mouth

In Matthew 12:34, Jesus is speaking directly to the Pharisees whose pretense and facade of apparent righteousness fell apart when they opened their mouths. Jesus rebuked them and explained, “You brood of vipers! How can you speak good when you are evil? For out of the abundance of the heart the mouth speaks.”

Out of the abundance of the heart, the mouth speaks. This is as straightforward as the previous verse. What you have been filled with will ultimately spill out of you. Whatever occupies your heart will control your tongue.

It would, perhaps, be simple enough to say that this verse simply warns us against foul language, swearing, and cussing. However, this verse means even more still. The context of this rebuke is the larger issue of how the Pharisees have blasphemed Jesus by accusing him of being demon possessed. Rather than praise Jesus for his miracles, the Pharisees blasphemed Christ by claiming “It is only by Beelzebul, the prince of demons, that this man casts out demons” (Matt. 12:24). What makes this language so wicked, sinful, evil, and blasphemous is that it lies about who Jesus truly is, while simultaneously ascribing the miracles he was performing to Satan. Such an accusation tried to rob God of his rightful glory while ascribing the glory to Satan instead. In the process of such a wicked accusation, the Pharisees revealed both their wicked hearts and their sinful allegiance to Satan.

Jesus, knowing this, said of the Pharisees in John 8:44 that, “You are of your father the devil, and your will is to do your father’s desires. He was a murderer from the beginning, and does not stand in the truth, because there is no truth in him. When he lies, he speaks out of his own character, for he is a liar and the father of lies.” Those who try to pretend to be righteous will, eventually, be revealed by their language. Their true colors will eventually show. They will, by mere words, reveal where their allegiance lies—whether they belong to Christ or Satan.

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