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Sermon on the Mount: Pure in Heart

Photo of Jeremy BaconJeremy Bacon | Bio

Jeremy Bacon

Jeremy is a divorced single dad who lives in Illinois with his three amazing children. He has a bachelors and masters in theology, which is not always super-useful at the retail job he's worked since 2006.

“Blessed are the pure of heart, for they will see God” (Mt. 5:8)

In Matthew 5:8, “pure of heart” is kind of a terrible translation. The word Jesus uses is straight-up the word “clean.” In Jesus’ day, there were very few concepts as theologically and even politically charged as being “clean.” The Pharisees evolved during the intertestamental period as a group meticulously obsessed with being “clean”—starting with the regulations in Leviticus and building from there. Unfortunately, the focus tended to be very external.

In all fairness, cleanness in the Old Testament is surrounded by external ceremonies. These, in turn, are prompted mostly by external situations—like skin diseases or gross things coming out of your body. Let’s be honest: the external is just easier to focus on. You can evaluate it almost instantly.

So, it’s shocking that Jesus works so aggressively to move beyond what’s external to get at what is internal.

Jesus absolutely goes to war against superficiality. This theme saturates the Sermon on the Mount. For most of Matthew 5, Jesus exposes the ways people try to keep the letter of the law while totally missing its heart. For most of chapter 6, Jesus argues that a purely performative religion has no lasting significance. For the rest of chapter 6, he shows that our concern for physical things reveals a heart that is off-center. Even in wrapping up the sermon in chapter 7, Jesus warns that an inside that is not transformed will eventually work its way out. At every step, the heart is what matters. Without that, the rest is pointless.

Elsewhere, Jesus explicitly confronts the Pharisees on this issue. “Blind Pharisee! First clean the inside of the cup and dish, and then the outside also will be clean” (Mt. 23:26). There is an extended discussion in 15:1-20 centering on the idea that “what goes into someone’s mouth does not defile them, but what comes out of their mouth, that is what defiles them” (15:11) because “the things that come out of a person’s mouth come from the heart” (15:19).

Then, in the very next story, Jesus meets a Canaanite woman who, pretty much by definition, has absolutely no externals right. Jesus heals her daughter anyway because he sees the woman’s (internal) faith (15:21-28). The earth-shattering turn that Jesus makes in his ministry is that he’s not concerned about cleanness on the outside. He’s concerned about cleanness “of the heart.”

Jesus absolutely goes to war against superficiality.

We modern English readers mostly get the idea of “the heart,” but the biblical concept is actually far richer than the English one. Yes, it includes our feelings (Gen. 6:6).

But it also includes the entire subterranean world of motivations that is usually inaccessible to us (Jer. 17:9). It’s tempting to call it the “subconscious,” but the biblical concept of “the heart” does not map well onto contemporary psychological models. It’s not that one or the other is wrong. They’re just looking at things so differently that you can’t fit one over the other.

For instance, “the heart” also includes our ability to deliberate and make choices (Gen. 27:41)—our choices being the most conscious of our prefrontal cortex activities. “The heart” can refer to almost any part of our inner life, or to the entire thing as a whole (Ps. 73:26). It can be a way of talking about our self, as deep as it goes. So it’s pretty close to an Eastern concept of the “core self” or the “essential self.”

That, says Jesus, is what needs to be clean.

So I’m toast. I look at my past, and I am well aware of ways I have defiled my heart. And the more Jesus opens his mouth, the worse it gets. Like the ancient Israelite who committed the “unintentional sin” (Lev. 4:1), I “become aware” (Lev. 5:5; 4:27-28) of levels of uncleanness that weren’t even on my radar. That’s painful. It’s hard to own up to the violence I have done to my own heart. (But if you’re a Pharisee, and your entire life’s mission, your very identity, is based on being ceremonially clean, it may be too much. Rather than face the reality of your heart, it may be easier to just make Jesus stop talking.)

So, the extent of damage done is a problem, but so is the depth. If the heart is so unsearchable, any attempt of mine to clean it out will almost certainly fall short. I’ll just be fooling myself. Without realizing it, I’ll be plastering over deeper layers that my devious inner mind just doesn’t want to deal with. A clean heart? How could that even be possible?

Let’s ask that ancient Israelite. Leviticus says an awful lot to him about becoming clean.

Take, for instance, someone who recovers from a skin disease and then brings a guilt offering to become ritually “clean.”

First, the guilt offering requires confession (Lev. 5:5). They have to acknowledge and own up to their sin.

Next, even in some of the simpler cases, they have to literally wash themselves and put on clean clothes (Lev. 15:5-8). In the case of a skin disease, they also have to shave their entire body (Lev. 14:8-9). That’s a little weird, especially for people who were very proud of their beards. They end up smooth like a baby. What do you do with a newborn baby? Wash it and put on fresh clothes. The idea may not be spelled out in words, but the picture is pretty clear.

This person is being born again.

That may be why Jesus was so stunned that being “born again” was a new concept to a scholar like Nicodemus. Anyone at the temple constantly saw people who shaved themselves bald, washed, and put on fresh clothes in order to become “clean.” How did he miss that?

Next, the person being cleansed is sprinkled in the blood of the sacrifice (Lev. 14:6-7, 14). Cleansing requires forgiveness (Lev. 4:31).

Lastly, they are anointed with oil (Lev. 14:15-18).

Or, as Peter summarized it for his Jewish audience who had just become aware of their sin,

“Repent and be baptized, every one of you, in the name of Jesus Christ for the forgiveness of your sins. And you will receive the gift of the Holy Spirit” (Acts 2:38).

In the face of all they’d done, Peter is telling them how to make their heart clean: confess, experience the washing of rebirth, find forgiveness in the blood of the Lamb, and let the anointing of the Holy Spirit do a new work of creation in you.

In Christ, our heart is clean because the Holy Spirit makes it entirely new.

As Ezekiel prophesied, God puts his Spirit in us, and this gives us a new heart (Ezek. 36:26-27). God does a new work of creation in us (2 Cor. 4:6), and we become a new creation, “The old has gone, the new has come” (2 Cor. 5:17). And this new heart, sprinkled by the blood of the Lamb, is clean (Heb. 10:22).

But we need to keep going and ask why we become clean. What’s the reason? Is it just for the sake of being clean—so we can feel better about ourselves? Or is it so that we can be good boys and girls? To be sure, if you make the tree good, it will bear good fruit (Mt. 7:17-18). These may be the features and benefits of Christianity, but they are not the purpose. It can get lost in all the details, but the goal of the Old Testament sacrificial system was fellowship with God. That which is holy cannot come into contact with that which is unclean. But we have a holy God who wants to dwell with his people (Lev. 15:31).

The capstone of all the sacrifices is the fellowship offering.

In any story in which all the sacrifices are offered, this is always the last one. And, in the culmination of the fellowship offering, part of the sacrifice becomes a feast that the worshipers symbolically share with God himself (Lev. 7:16). THIS is the goal of atonement—to be in the presence God. This is why David asks for a clean heart. “Do not cast me from your presence,” he says (Ps. 51:10-11). A heart that is set right recognizes that this is the only thing that really matters.

In this Beatitude, all of life melts away. There is no status, no career, no possessions, no endless ways of passing the time. There is only a person, at the core of their being, standing before their God. In the Old Testament, seeing God was unimaginable. Ritual cleansing can only get you so close. But the promise of the New Covenant is that it reaches to the depths of who we are and literally, metaphysically makes us new. Now, with our hearts clean, our focus is neither external nor internal.

Our focus is on Him.