What Does It Mean to Guard My Heart? How Can I Do That?

What does it mean to guard your heart? Today, Michael Reeves explains the biblical definition of the heart and how feeding on God’s Word shapes our spiritual lives.

NATHAN W. BINGHAM: We’re recording live from Ligonier’s 2024 National Conference, and we’re joined by Dr. Michael Reeves. And he serves as president and professor of theology at Union School of Theology. Dr. Reeves, what does it mean to guard my heart, and how can I do that?

DR. MICHAEL REEVES: To understand that, we really need to define what the Bible means by the word heart, and that can be usefully seen in how Jesus speaks about the heart in Matthew 15. So, in Matthew 15, Jesus says that it is out of the heart come those sinful actions that defile us. It is not what goes into our body that defiles us, but what comes out of the heart (Matt. 15:18–20).

And you could say, “Well, what exactly is that heart? Something within me?” James 1 says it is desire that gives birth to sin (James 1:15). So, Jesus says “heart;” James says “desire.” So, when we talk about the heart, we are talking about the very center of our spiritual being. But it is a center characterized by our desires, which is why it is central—because our desires shape everything we do. So, Proverbs 16: in his heart, a man plans his course (Proverbs 16:1, 9). We tend to think that’s about the brain, but actually, I plan my course according to what I want. So, my heart is all about my desires and corrupted by sin, therefore, out of these sinful desires, obviously, comes sinful actions. Desire gives birth to sin.

So, when Proverbs 4 talks about guarding the heart, it’s talking about guarding this seat of desires that will latch onto, lust after, want what is put in front of it. And what Proverbs 4 is advising—is commanding, even—is that we should be very careful to watch what diet, what spiritual diet we feed our hearts. And the context for that verse, in fact, for guarding the heart—Proverbs 4 context—a couple of verses before say:

My Son, be attentive to my words;
incline your ear to my sayings.
Let them not escape from your sight;
keep them within your heart.
For they are life to those who find them,
And healing to all their flesh.
Keep your heart with all vigilance. (Proverbs 4:20–23)

So, the way to keep your heart is to ensure the diet it’s receiving is the pure life-giving words of Scripture. It’s feeding it healthy food so that, seeing more of scriptural truth, my desires are woken up to healthy spiritual things. The flip side to that is, if I don’t feed my heart with scriptural truth, if I feed it with junk from the internet, if I feed it with worldly ambitions and desires, I’m training it to desire sinfully.

So, what you look at, what you feed on, will shape you; it’ll shape your desires. And Proverbs is saying: “Well, your desires will bring forth sin and death or life and righteousness. Therefore, feed your desires with the right food.”