The aspiration of polyamorists to win social acceptance is being led by the most unlikely political vanguard: Christian churches.

Polyamory, also known as consensual non-monogamy, is the practice of having multiple romantic or sexual partners concurrently, with the consent of everyone involved. It remains taboo in much of the West, but the issue has become particularly salient in progressive-leaning churches.

Last month the governing body of the one-million-member US Presbyterian Church voted on whether pastors must be monogamous, or if they can live in polyamorous relationships. The committee overwhelmingly voted to keep the issue alive, allowing a further two years of “prayerful reflection” for pastors to hone their Biblical arguments and counter-arguments.

According to one priest, April Stace, polyamory is an issue that “all mainline denominations will need to address in the coming years, as non-monogamous relationships continue to gain more visibility within the United States”. Stace argues that the debate will follow the same moral trajectory as earlier debates over divorce, interracial marriage, women’s ordination and same-sex relationships.

And it’s not just the Presbyterians. According to Religion News Service, an Episcopal Church task force in 2024 argued that “diverse family and household structures” needed to be confronted in the church. One proposed resolution offered limited disciplinary protections for clergy and laity after several non-monogamous Episcopal priests renounced their ordination vows amid conflict within the denomination.

The growing appeal of non-monogamous relationships led the Vatican to reject polyamory and polygamy, the practice of having more than one spouse at the same time, in a doctrinal statement last year. Religion News Service said the doctrinal document was the first time that the Vatican felt compelled to address the growth of polyamory in the West, affirming that monogamy is an exclusive and “indissoluble union” between a man and a woman.

One of the arguments for polyamory is that the practice is inseparable from queerness. That was the claim made by the advocacy group More Light Presbyterians in response to the question of polyamorous pastors: “While framed in the language of faithfulness, it risks reinforcing narrow and culturally bound definitions of relationship that have historically been used to exclude, police, and harm queer bodies and lives.”

Then there are the Biblical arguments. Within this theological framework, “mononormativity” is seen as exclusionary, hierarchical and judgemental, whereas polyamory reflects the radical acceptance and divine grace embodied by Jesus. “The very nature of Jesus’s ministry suggests the abolition of exclusive norms,” theologian David Congdon wrote last year. Hence the early Christian community’s decision to share all possessions in a communal spirit. “If one’s material goods ought not belong exclusively to one person,” Congdon wrote, “how much less should a fellow human being be viewed as exclusively belonging to another?”

There are signs that the polyamorists are already making inroads in some churches. The Evangelical Lutheran Church in Canada declined to suspend a minister in a polyamorous relationship in 2023. Unitarian Universalists and the United Church of Christ, meanwhile, have sponsored support programmes for polyamorous parishioners.

If the past is prologue, mainline Christian denominations will eventually make allowances for polyamorous pastors and poly marriages. And when they move in that direction, another generation of centrists and conservatives will walk away.