It is one of the strangest things in the Bible: purity laws. Strange, because it is not at all part of our way of life. Geoffrey Harper, who teaches at Sydney Missionary and Bible College, published a book about it in 2025: ‘You Shall Be Clean’: A Biblical Theology of Defilement and Cleansing (paid link).
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For many pages, for as long as it deals with the Old Testament, it is superb. It has a keen eye for details in the biblical text. From it, Harper uncovers a crucial distinction. There are two systems or categories of ‘unclean’. This distinction he finds in the text; it is not something imposed on it later, the way scholars distinguish between ‘ritual’, ‘civic’, and ‘moral’ laws.
The final one third of the book, which turns to the New Testament and concludes with a chapter claiming to present “A Biblical Theology of Defilement and Cleansing” … Well, that’s a different story. More about this later. First, the good stuff.
What Makes Unclean?
Harper begins, and so will we, with the basics. In Leviticus, if a woman has her period or gives birth, she becomes unclean. There is nothing she can do to prevent it. As with any form of impurity, this disqualifies her from approaching the tabernacle.
Touching a corpse makes you unclean as well. You may be able to prevent this, but that may not be right. Someone has to prepare the deceased for burial, and in the case of a parent, this responsibility naturally falls to you.
Certain diseases, mold, and skin conditions make unclean as well, and again, there is nothing you can do to prevent it. And then there are unclean foods: animals one should not eat. There, at least, one has a choice.
Scripture never explains why these things make a person unclean. It has been suggested that it may be items linked to the cycle of life and death, seeing this would cover most causes of impurity, but Scripture itself is silent.
It is important to realise impurity is not sin; it does not make one guilty. And the law provides remedies.
For lighter forms of impurity, simply waiting and taking a bath make one clean again. For more severe forms there are various rituals that will cleanse a person. In the case of defiling disease and skin conditions, this will only work after the cause of the impurity is no longer present or active.
Type 2: Another Kind of ‘Unclean’
After presenting these basic facts from Leviticus, Harper (2025: 31ff) goes on to document a second type of impurity. It is not tied to biology or circumstance. Instead, it is caused by behaviour that is forbidden in the law and that may even be considered an “abomination” (see esp. Lev. 18-20).
Here, one obviously does have a choice; it does not just ‘happen’ to someone. And the resulting impurity is in principle permanent. There is no remedy for deliberate or ‘high-handed’ sin, sin in conscious defiance of God.
Yet another difference: this type does not ‘infect’ others. It is not passed on the way the first type is. Touch a menstruating woman and you become unclean for a day. Touch a corpse and you will make others unclean when they touch you. But you won’t become unclean by touching a murderer or an adulterer.
The same terminology is used but these are two distinct forms of impurity.
In the law, not every deliberate sin makes a person unclean. Stealing, for instance, does not. The defiling aspect appears to be limited to sexual sin, murder, and idolatry (ibid.: 37; see Lev. 18; Nu. 35:33).
However, this category of impurity does pollute the land and the sanctuary, which the first type does not (unless the unclean person enters the sanctuary).
Harper (Ibid.: 42) adopts the terms ritual and moral impurity to distinguish the two categories. He argues that it is not clear whether one category is older than the other and perhaps gave birth to the second one. Already in Leviticus, both are present and discussed extensively. I find it easier to imagine a way from ritual to moral impurity than the other way around; when it comes to remedy, this is certainly the direction of development, as we will see below. I admit, however, that we cannot know this for sure.
In summary:
| Ritual Impurity | Moral Impurity |
| Usually unavoidable | Avoidable |
| Not a sin | Serious sin |
| Can be passed on | Cannot be passed on |
| Does not pollute the land | Pollutes the land |
| Remedies provided | No remedy provided |
Is Impurity Real?
As noted, Scripture does not explain what, exactly, impurity is. However, this may be the most crucial question. Is impurity something ‘real’, something that exists almost like a physical substance? This is the so-called essentialist view. But if so, what is that ‘something’? Or is it symbolic – the non-essentialist alternative?
Harper (ibid.: 42-44) presents an overview of the many conflicting opinions on the reality (or not) of impurity. Strangely, he goes on to conclude: “Thankfully, resolving the issue is not crucial … the terms still fulfill important literary, rhetorical and theological functions, which can be assessed” (ibid.: 44).
This is partially true, but we do need some understanding of the essential nature of impurity; otherwise, we cannot assess what – if anything – we are to do about it today.
Of course, the two types may differ on this point of their nature; I would argue they do. Moral defilement is a metaphor for something that is very real: the guilt and disqualification that sin causes. It’s like dirt.
Ritual impurity, on the other hand, is not real. Otherwise, how could ritual purity be dropped so easily in the New Testament as a prerequisite for entering God’s presence? How could we be the temple of God and have our period or touch a corpse? As I argued in a previous issue, the distinction between clean and unclean may well be a human invention, already in place, that God adopted – for a limited time.
This view finds support in the passage on dealing with ‘leprosy’ in houses:
Then the priest shall command that they empty the house before the priest goes to examine the disease, lest all that is in the house be declared unclean. And afterward the priest shall go in to see the house. (Lev. 14:36; Harper refers to this verse in a footnote on page 44 of his book)
Nothing essential changes by the priest’s declaration that may follow the inspection, yet the impurity of the house now becomes contagious, whereas the person – and everything else – that were in the house just before the declaration remain clean. This does not make sense if impurity has objective (‘real’) existence.
Ritual and Moral Impurity in the New Testament
How are these two categories that are so distinct in the Old Testament treated in the New Testament? With this question, we come to the part of the book I dislike. It is not simply because I disagree with Harper, although I do. I find Harper unclear on what he believes about ritual impurity under the new covenant. Is it still a relevant category and practice that should be observed in some way? Moral impurity is, but ritual? And if so, what are the implications? What are we to do about it?
When it comes to salvation, the New Testament often uses the language of purification and cleansing, at length in Hebrews, but also in other places (e.g., Tit. 2:14; 3:5f; 1 John 1:7, 9; 1 Pet. 1:22). But is this literal? And does it deal with moral defilement only? Or do we also need cleansing from ritual defilement?
And regarding practice under the new covenant, is ritual impurity, in the language of Jesus in Matthew 5:17, “fulfilled” (not abolished)? Are its regulations subsumed in higher categories and demands? Are they remedied by life in the Spirit and therefore not relevant? Or is ritual impurity still an issue?
It appears Harper thinks it is, although his statements leave me somewhat uncertain. I will place two examples from his book in an appendix, to give you a taste in case you want to know more. To me, Harper sounds as if he believes in the continuing validity and importance of ritual impurity as a category.
This raises questions screaming for an answer that Harper does not seem to hear. For instance, assuming I understand Harper correctly, sexual intercourse and other things still cause impurity, in his view. The implications are immense, but they are not explored, not even in the final chapter, although its subject, “A Biblical Theology of Defilement and Cleansing”, would seem to demand it.
It seems to me that the New Testament shows no concern whatsoever related to ritual defilement. Paul has much to say about maintaining moral purity but does not instruct the church on ritual purity and purification as something it should heed. Except in the context of helping Jewish and Gentile believers to get along, where food items may be a stumbling block for fellowship (Rom. 14f), it is not an issue.
So, What Is the Point?
If ritual purity has no objective existence and is not an issue for Christians, as I argue, what purpose did it serve? Why did God institute such an elaborate system? A few thoughts in closing.
1. This taught Israel – and teaches us – to think in clear categories of clean and unclean, right and wrong.
2. It helped Israel to be aware of and maintain its status and identity. The system provided identity markers, to keep Israel separate from the nations. Under the new covenant this is no longer necessary, because Jewish and Gentile believers now form one community in Christ.
3. It gives the distinction an emotional dimension. It works on a gut level, by inculcating a sense of repulsion. This is more effective than rational arguments. The purity system shapes the moral imagination. It trains the instincts, not just the mind.
In part, these emotional reactions – what is repulsive, what is an abomination, what defiles, and what does not – are cultural. Still, ritual impurity includes things that most of us find repulsive by nature. And once the distinctions are established in a culture, the visceral reaction of disgust will automatically manifest itself.
What is not cultural is our disgust and repulsion at some things. This is human; all cultures have this.
This framework – of abomination and defilement, with their repulsive nature – carries over to the other form of impurity. We learn, and feel, that sin is repulsive, it defiles. Yak! The purity laws of Leviticus help us grasp this on a deeper level than straightforward moral instruction.
4. According to the law, ritual impurity can be removed. This stirs up longings and even hope: if ritual impurity can be washed away, perhaps moral defilement can be cleansed as well. Is that possible? The prophets envisage such a solution:
I will sprinkle clean water on you, and you shall be clean from all your uncleannesses, and from all your idols I will cleanse you. (Ezek. 36:25)
And when David is stricken with remorse over his act of adultery and murder, he, too, uses the language of ritual purification to beg for moral cleansing:
Wash me thoroughly from my iniquity,
and cleanse me from my sin!
(…)
Purge me with hyssop, and I shall be clean;
wash me, and I shall be whiter than snow. (Ps. 51:2, 7)
As Harper rightly points out: “The psalmist expects God can do what humans cannot” (ibid.: 113). And so it turns out to be: the blood of Jesus cleanses us from all sin. Cleanses, purity language. What David asked for, we, too, have received.
See also Sacrifices and Purity Laws: Do We Need a Red Heifer?
Appendix
For those wanting to know more: here are the two examples from the book I announced earlier. In the first, Harper makes a distinction between Jesus healing a leper and the man’s cleansing as a second step, to be accomplished by a priest:
Irrespective of the man’s reasons for doubt, Jesus’ words (‘Be clean!’) and subsequent instruction to enact sacrificial cleansing ([Mk.] 1:44) signal his upholding of ritual categories. Therefore, the episode does not indicate a reversal of defilement, with Jesus purifying the lepros by touch. If that were the case, there would be no need for priestly purification rites. Instead, the passage reveals Jesus doing what Israel’s priests could not: healing ṣāraʿat/lepra. Jesus overcomes the source of impurity, preventing re-pollution. (Ibid.: 156)
Jesus would heal, but could or would not purify? As I see it, Jesus simply honours OT protocol; at this point, he is still operating under the old covenant. The priest does not so much cleanse the leper as establish his status as ‘clean’ – remember the house in Leviticus 14:36. Jesus did not say, “Be healed!” He said, “Be clean!” (cf. Mt. 10:8, to the disciples: “cleanse lepers”).
The second example concerns the question of the Sadducees about marriage in the resurrection (Mk. 20:27-40):
If becoming ‘like angels in heaven’ relates to [a priestly role in the heavenly sanctuary], then heightened purity requirements explain the absence of marriage in the eschaton as well as Luke’s addition, ‘they can no longer die’ ([Mk.] 20:36). Because death and sexual intercourse defile they are inappropriate for those serving in God’s sanctuary. (Ibid.: 162; see also 190, where Harper refers to “the ritual impurity generated by sexual acts”)
Sex – and other things – defile? It makes one wonder how we can worship in God’s presence today. And how can we be a temple of the Holy Spirit? Pointing to the purifying presence of the Spirit (discussed by Harper on page 169-171) does not suffice; this would be true in heaven as well. But Harpers offers not a word of explanation or comment.
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References
Unless indicated differently, Scripture quotations are from The Holy Bible, English Standard Version®, copyright © 2001 by Crossway Bibles, a publishing ministry of Good News Publishers. Used by permission. All rights reserved.
Harper, Geoffrey. 2025. ‘You Shall Be Clean’: A Biblical Theology of Defilement and Cleansing, New Studies in Biblical Theology Series, 65 (London: Apollos) (paid link)
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