If I could have a superpower, I would want to be able to speak with such force that the things I say actually happen: instantly, completely, and as beautifully as I imagined. I know that I currently do not have this power because I have four kids. I speak clear, simple, direct instructions like “Put on your socks and shoes so we can leave!” and no one moves. My words must fall to the ground and shatter. Or perhaps they just evaporate into the clouds before they reach their ears. The point is, I am capable of speaking words but my words do not always make things happen.

In fact, my words do not often make things happen. I can speak my good intentions out loud, but nothing is going to happen unless I put in the work. If I want to be better at controlling my temper, it isn’t enough for me to just say out loud that I would like to be better. I have to do the work

This is one of the differences between God and I. When God speaks, his words are “powerful and effective” (Heb. 4:12) and they make things happen. He created the world through the power of his speech. He proclaims “let there be light” (Gen. 1:3), and the very molecules obeyed to form the heavenly bodies that govern our days and guard our nights. I can’t even get my kids to obey, and God can command the elements to combine in different forms, ordering themselves into oceans and dry land and all the variety of plants and animals who live there.

When a promise of God seems slow to be fulfilled, I remind myself that once God speaks, his words are already being fulfilled. The universe obeys his commands, so His promises are all true. Unlike human beings, God is incapable of lying (Num. 23:19). He cannot separate His words from His deeds, because His words make things happen.

Human beings, however, can separate our words from our deeds. We can say we’ll do things that we don’t actually intend to do or can’t do. We can fail to live up to our word. With this in mind, Jesus instructs those listening to his Sermon on the Mount to be careful about how they use their words. He reminds us not to make promises to God unless we are going to follow through: “You shall not swear falsely, but shall perform to the Lord what you have sworn” (Matthew 5:33). He also commands us to be just as cautious in our dealings with one another. We should not make promises we won’t or can’t keep. We should not try to add weight to our words by making dramatic oaths. We ought not to swear on the glories of creation that we didn’t form and don’t own: “Do not take an oath at all, either by heaven… or by earth…or by Jerusalem…and do not take an oath by your head” (Matthew 5:34-36). There is no value in lofty promises, therefore we shouldn’t make them.

It is our follow through that matters, as Jesus illustrates later in Matthew through the parable of the two sons: One says he will not obey his father’s command to work in the vineyard, but then he does. His brother says he will work, but never goes out to work. It is the first who actually did what his father wanted (Matthew 21:28-32). Our actions speak louder than our words. Therefore all we need to say is a simple “yes” or “no.”

Jesus wants his listeners to be people who say simply and clearly what they are going to do. If they say Yes, they ought to do what they’ve said they will do because “Anything more than this comes from evil” (or “the evil one”). The ability to lie, to speak words that are different from our actual intentions, comes not from our heavenly father who cannot lie or change his mind (Num. 23:19) but from the father of lies. When we allow our words to differ from our actions, we are indeed imitating the devil, who “when he lies…speaks out of his own character, for he is a liar and the father of lies” (John 8:44). The contrast between our God and the devil is stark: scripture tells us that “it is impossible for God to lie” (Hebrews 6:18) but that the devil “does not stand in the truth, because there is no truth in him” (John 8:44). One can only tell lies and one can only tell the truth.

Jesus calls us to imitate our true Father by speaking clearly what we intend to do and then obeying our own words. When we speak truly, we proclaim ourselves to be the children of God. When we speak truly, we join in all of creation in proclaiming that God’s words are true and his covenants can be trusted because he speaks the truth.