What is Jesus’ R0 factor?
In this time of COVID-19, we’ve all learned some new words; words like spike proteins, viral load, and hydroxychloroquine.
One of these new concepts—the R0 factor—measures contagiousness. How close must one be to an infected person to “catch” what they have? Is the contagion passed primarily by blood, saliva, or has it been aerosolized? Can it live on surfaces?
In the early days of the pandemic, while my asthmatic son was dealing with some breathing trouble—I took the extreme step of constructing a cleaning station in our garage where I would wipe down our groceries (and mail) before they entered the house.
But what does any of this have to do with Jesus?
JESUS AND THE FORCES OF DEATH
One of the best books I’ve read this year was Jesus and the Forces of Death, by Matthew Thiessen. The text focusses on the Gospels’ portrayal of ritual impurity–and it argues, in line with scholars like Jacob Milgrom, that the Jews associated these impurities with forces of death.

The Law of Moses taught that certain substances rendered one ritually unclean. These contagions included genital discharges, skin diseases (lepra), and corpses. To be ritually impure was not sinful. But it meant that one was barred from approaching God’s presence (for instance, in the temple) until one had undergone purification.
Ritual impurity comes up repeatedly in the Gospels:
• Jesus touches lepers and they are cleansed.
• Jesus encounters corpses and they rise.
• Jesus faces impure spirits and expels them.
But there is one story for which Thiessen’s work is particularly illuminating: Jesus and the bleeding woman (Matt 9:20–22; Mark 5:25–34; Luke 8:42–48).
JESUS AND THE ZAVAH
In Hebrew, the zavah was a female “discharger”—a woman with chronic flow of menstrual blood.
As with other bodily discharges, Jewish Law maintained that no one could touch the zavah (or even her bedding) without being rendered impure (Lev 15:25–27). Even one’s clothing must be purified if it had potentially been contacted by such a woman.
Then in Mark’s Gospel, we read of a woman who had been bleeding for twelve years:
27 When she heard about Jesus, she came up behind him in the crowd and touched his cloak, 28 because she thought, “If I just touch his clothes, I will be healed.” 29 Immediately her bleeding stopped and she felt in her body that she was freed from her suffering.
30 At once Jesus realized that power had gone out from him. He turned around in the crowd and asked, “Who touched my clothes?” (Mark 5:27-3)
THE HOLY CONTAGION
In Thiessen’s words,
“The story implies that Jesus’s body can function like an unthinking force of contagion that inevitably destroys impurity” (7).
Instead of Jesus being made unclean by the woman’s touch, the opposite happens: The source of her impurity is healed, because Jesus embodies a contagious form of holiness and purity.
Incredibly, Jesus never decides to heal the woman. He merely notices that power has gone out of him, and then inquires, “Who touched my clothes?” (v 30)
So I ask again, what is Jesus’ R0 factor?
HOLINESS BEYOND SEGREGATION
We often think of holiness as something that is maintained by separation: “social distancing” if you will. For indeed, to be holy meant to be “set apart” by God for special use.
But Jesus’ holiness challenges the exclusivity of this notion. Christ’s holiness is contagious; it is not merely a fenced off and fragile status. Jesus’ holiness goes on the offensive. It heals the sources of impurity, and yet (apparently) without itself being defiled.
Never is this truer than in Christ’s crucifixion—in which the forces of death come calling for his own body. Yet even in death, Christ’s corpse emits a purifying power.
This point is seen most notably in the strange passage from Matthew that describes how Christ’s final breath brought the corpses of many holy ones to life within their tombs (Matt 27:50-53). (See here for my post on that unusual passage.)
There is some prophetic precedent for this kind of holiness. But not much. Elijah raises a widow’s son after laying his own body atop the boy’s (ritually impure) corpse. And Elisha unwittingly raises another dead man after the man’s corpse is thrown into a grave containing Elisha’s bones. (Happy Halloween!)
Still, Thiessen’s claim is that Jesus’ contagious holiness is unequaled in the Scriptures.
CONTAGIOUS HOLINESS TODAY
As a work of biblical scholarship, Thiessen’s book does not intend to make the turn to contemporary or pastoral application. But I’d like to gesture in that direction: What does Jesus’ contagious holiness mean for us today?
Incidentally, I come from what is often called a “holiness tradition”—and specifically, from a denomination that has roots in the revivalism of John Wesley, in abolitionism, and in women’s suffrage. I’m proud of that.
But in my own holiness tradition there has sometimes been a failure to learn the lesson of Jesus’ R0 factor. We saw holiness as something “set apart” and fragile—but not as something that is powerfully contagious.
In fact, holiness is both.
Elements of the holiness tradition propounded legalistic and extra-biblical rules on everything from wedding rings, to hairstyles, to alcohol—but we did not always grasp that Christ’s holiness is something that was spread by CONTACT with an unclean world, rather than by mere segregation from it.
This point requires discernment.
SET APART FOR SERVICE
There are times in which separation is required.
Moral impurity is not healed by uncritically immersing ourselves in environments where it is glorified. When we cozy up to wicked leaders and excuse their abusive and arrogant behavior in the attempt to gain “influence”—we deceive ourselves. Holiness doesn’t spread like that.
And yet, to be Christ’s body—filled with his Spirit—seems to imply that we might also view holiness in contagious rather than defensive terms.
Christians are, as it were, “set apart” for service.
In the holiness tradition, the group that most clearly embodies this holiness-on-the-offensive posture has been the Salvation Army. But it is a shift in perspective that is important for all Christians.
Impurity isn’t cleansed by pretending it does not exist (Liberal relativism). Nor is it healed by mere separation (fundamentalist escapism). Whether it is ritual or moral impurity, the solution comes by transformative CONTACT with the Holy One of God–or at least the fringes of his garment.
Get Matthew Thiessen’s excellent book here–and stay tuned for an upcoming interview with him on my podcast, Outpost Theology.
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Want to support this blog? Here are some other things I’ve written:
- Long Story Short: The Bible in Six Simple Movements (Seedbed, 2018)
- The Mosaic of Atonement: An Integrated Approach to Christ’s Work (Zondervan Academic, 2019)
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