In today’s Gospel, Jesus offers a series of vivid images to help his disciples understand the kindom of Heaven. (Our translation, The Inclusive Bible, prefers “kindom” rather than “kingdom,” for the Greek word basileia, following the insights of feminist theologians who see kinship, rather than patriarchal monarchy, as characteristic of the ways that God is at work in the world, already but not yet – the promise of what is already happening and what is to come.) We may be more familiar with the “sower” and “mustard seed” analogies, but what are we to make of that last image, just a single sentence long – “The kindom of Heaven is like the yeast a baker took and mixed in with three measures of flour until it was leavened all through?”

This yeast metaphor was a favorite of the French theologian Marie-Dominique Chenu (1895-1990). Chenu began his education in the early 20th century, when the institutional Catholic Church had taken a largely defensive stance against the developments of the modern world, fearing that scientific and political revolutions threatened its doctrinal and temporal authority. But drawing on Jesus’s likening of God’s kindom to yeast in dough, Chenu resisted this tendency to withdraw from or condemn the “outside world,” insisting that the church’s very mission is to engage the world. Retrieving this biblical image from the Gospel of Matthew, Chenu argued that the Christian community ought to immerse itself in even seemingly secular sectors, attuning ourselves to where God may already be at work outside the confines of the institutional church. 

Throughout history, church leaders have worried about institutional preservation – how to protect the church from external threats. In his 1940 article “Social Classes and the Mystical Body of Christ,” Chenu recognized this temptation to keep the church somehow uncontaminated by the realities of the world: “Sometimes, I fear, we only think of the Gospel’s power as a pious escape from earthly constraints. . . and we then hesitate to toss the yeast fully in the dough, fearing that if we did, we wouldn’t be able to conserve religious purity.” But, he argues, the church’s job is not to protect itself by being set apart. Rather, we are to go out into the world, bringing the Gospel leaven into it. Yeast seems to vanish into the dough mixture, but that is where it really begins to work. The true power of yeast is not clear until it has been fully immersed into the other ingredients. Similarly, the true power of the Gospel is not actualized until it is immersed in the world. In 1954, Chenu asked rhetorically, “If the yeast isn’t in the dough, what good is its untouched purity?”

Chenu ties this yeast imagery to the incarnation: in the human person of Jesus, God fully enters human reality. God did not flee from or abandon the messiness of earthly realities; on the contrary, God took it all on by becoming human. If this is how God works, and Jesus tells us that this is how God’s kindom works, then so too, Chenu insists, should the church, in service of the kindom.

Chenu embodied this commitment in his own life, particularly in his engagement with the French poor and industrial working class. Chenu sent his seminary students outside the walls of the Dominican House of Studies to take on manual labor internships. He served as the unofficial chaplain of the Worker Priest Movement – a group of priests who left their comfortable parish positions in favor of full-time manual labor. He theologized with worker communities, noting in his 1975 interview with Jacques Duquesne that they “weren’t asking for a solution from on high,” but “wanted [Chenu] to help them find Christian solutions for themselves, out of their own experience.”

While Chenu’s vision of a church engaged with the world, like yeast immersed in dough, initially incurred suspicion from Rome, this idea was largely embraced at the Second Vatican Council. The document Gaudium et spes, “The Church in the Modern World,” recognized the church’s “duty of scrutinizing the signs of the times and of interpreting them in the light of the Gospel” (4). In today’s Gospel, we hear an invitation to fully immerse ourselves in the signs of the times, to serve as leaven in the world, and to discern where God might already be at work.

Marie-Dominique Chenu (1895-1990) was a French theologian, medieval historian, Dominican priest, and advocate for the working class. His early work focused on the cultural and historical context that shaped Thomas Aquinas’s thought, and evolved to take on a sharper social consciousness. While the Vatican initially condemned both Chenu’s historical work and his advocacy for the Worker-Priest Movement, many of his ideas came to be embraced at the Second Vatican Council, where he served as an advisor to the African bishops. His most notable works include Saulchoir: A School of Theology (1937), Toward Understanding St. Thomas (1950), and Theology of Work (1955).

Cartoons often depict God as a white man in the sky, who occasionally intervenes in the world with a bolt of lightning or a divine decree. But this is not the God whom Jesus describes in today’s Gospel!

Jesus tells us that God’s kin-dom is like yeast in dough. We invite you to meditate on this image, in all of its physicality. Smell the earthy aroma of yeast. Feel the texture of the granules of kneading yeast into flour, water, and salt to prepare bread dough. Contemplate the time that yeast takes to work – how the dough slowly but surely expands, swelling to more than double its original size. 

As this image permeates your senses, turn your attention to God. What does it mean to you that God acts in this way, like yeast in dough? Where in the world, if you pay close enough attention, do you see God’s kindom unfolding like this? What sectors of the world do you feel called to immerse yourself in, acting as the leaven of the Gospel?

From 1943-1954, 100 French Catholic priests eschewed Roman collars in favor of denim factory uniforms, renouncing the trappings of clerical distinction to live and labor with the working class. Recognizing that ecclesial structures established to serve agrarian medieval society had failed to address the radical new living and working conditions of the Industrial Revolution, these “worker priests” entered into solidarity with the working class, who had largely turned away from the Catholic Church. They took on full-time jobs as dock workers in port cities; metallurgists in factories; firemen at industrial furnaces; and construction workers at hydro-electric dams. There was even one technician in the film industry.

Initially spurred by a mission to evangelize the laborers, many worker priests found their vocation transformed, becoming advocates for labor rights and social justice. Struck by the dehumanizing injustice of housing and working conditions, the priests joined unions. Notably, they chose the openly communist General Confederation of Labor (CGT) rather than the explicitly religious French Confederation of Christian Workers (CFTC), because the majority of workers favored the former. Some even took on leadership roles, organizing strikes and participating in confrontations with police. 

Marie-Dominique Chenu served as the unofficial chaplain and theologian of the Worker Priest Movement. Although the movement was dismantled by the Vatican in 1954 – fearing they were communist sympathizers and had strayed too far from a traditional understanding of priesthood – these men stand as witnesses that a radical form of Catholic ministry, building the kindom of God like yeast in dough, is possible.

For more on this movement, see Oscar Arnal, Priests in Working Class Blue: The History of the Worker-Priests (1943-1954).

Fritz Eichenberg’s “The Labor Cross” (1954) is a wood engraving that features laborers of different races, genders, and ages, all positioned within the framework of a large wooden cross. They till, build, fish, and mine. Eichenberg (1901-1990) was a German Jewish illustrator who fled Nazi occupation in 1933. He dabbled in many religious traditions and joined the Society of Friends (Quakers). Through his friendship with Dorothy Day, he contributed many illustrations to the Catholic Worker newspaper. His art often features themes of labor and pacifism.

Image description: On a large grained cross stand workers, one with a net, one hoeing a field, some stewarding animals with their children, one cutting beams with a large saw, one using a pick, wearing an old-style mine helmet, and one cutting down a tree with an axe.