On Sunday, in LDS wards across the country, Mormons received instruction about their church’s ongoing fight against same-sex marriage. Two days earlier, the First Presidency, the LDS Church’s highest ranking authority, distributed a letter to all congregational leaders to be read during church services. Acknowledging the recent events in Utah, the memo reminded Mormons that heterosexual marriage “was instituted by God” and that LDS officials would not perform same-sex marriages nor would any Mormon buildings be used for such purposes. The missive also directed congregational leaders to review with members, “The Family: A Proclamation to the World,” a document the church produced in 1995 that has appeared at times of social crisis ever since.

Why has the LDS Church chosen this moment to redeploy a nearly 20-year-old document? And what does “The Family”—a document that never explicitly mentions homosexuality or same-sex marriage—reveal about Mormon officials’ sense of the real crisis facing the LDS Church today?

Understanding the creation and history of “The Family” not only helps us appreciate the particular logic of Mormon objections to same-sex marriage but also clarifies the larger issues at stake for the LDS Church in this matter. In 1993, after two decades of bruising internal theological and political battles over questions regarding gender and church authority, the LDS Apostle Boyd K. Packer told a group of church bureaucrats that the three greatest threats to the faith of Mormons were intellectuals, feminists, and the gay-rights movement. The church quickly organized against gay rights. As states across the nation took up Defense of Marriage Act legislation in the 1990s, the LDS Church moved to the frontlines of those battles, playing a pivotal role in nearly a dozen state contests.

“The Family,” issued as the church began these fights, linked the Mormon theology of salvation rooted in the traditional heterosexual family unit to the civil rights question of gay and lesbian Americans without even acknowledging their existence. Mormon salvation—or exaltation to the Celestial Kingdom—requires that male and female Saints enter into a temple-based marriage and enact, as “The Family” describes, the “divine design” of their respective gender roles. Men are to “preside over their families” while women are “primarily responsible for the nurture of their children.” Together, they are to fulfill their religious responsibility to reproduce, creating an extensive earthly family that will be joined together eternally in the afterlife.

Same-sex marriage, of course, challenges all of this. While Mormons agree with other opponents of gay marriage that its legalization is “unbiblical” and a threat to the traditional heterosexual family unit, LDS objections also arise from the core of Mormon theology and its particular interconnection of heterosexuality, marriage, and salvation. In short, same-sex marriage threatens the basic foundations of Mormonism. This is why “The Family” has been such a critical document for the LDS Church in its fight against same-sex marriage for the last 20 years and why the church has repeatedly reissued the document at other critical moments in the marriage equality battle, including in 2008 during the height of the church’s involvement against California’s Prop 8. By instructing Mormons about heterosexual marriage as a divinely-created institution essential for their own salvation, “The Family” and other LDS teachings construe the fight against same-sex marriage as a defense of their faith rather than an assault on the rights of gay and lesbian Americans.

All religious leaders have to connect theology to social issues in order to justify and mobilize political activism from their members, of course, but the LDS Church’s continual use of “The Family” has purposes beyond the same-sex marriage fight. Despite Mormons’ conservative reputation and voting patterns, there’s increasing evidence from grassroots Mormons that they are not as exercised about same-sex marriage as their leaders are. A 2012 study from Brigham Young University found that only 29 percent of Utahans said same-sex relationships should enjoy no legal recognitions. This was down from 54 percent in 2004. The organization Mormons Building Bridges, which drew attention two summers ago for marching in several gay pride parades, has pushed for greater tolerance in the church toward gay and lesbian members, though it has notably avoided taking a stance on same-sex marriage. Other Mormons have offered full-throttled support for marriage equality.

Whether ambivalent, resigned, or supportive, Mormon acceptance of gay marriage challenges the church’s authority, a core component of LDS belief. Church leaders have continually described gay marriage as a “moral” rather than political issue. If LDS leaders are unable to command solid opposition to same-sex marriage from the Saints, then its leaders’ prophetic status and moral authority has been weakened. This is a crisis the LDS Church faced when some of its members became vociferous critics of the church’s efforts against the Equal Rights Amendment in the 1970s. The church dealt harshly with those women not because they supported the ERA, church leaders explained, but because they had publically challenged the church president’s prophetic role—a key tenet of Mormonism. Increasing societal support for same-sex marriage suggests another crisis moment for the LDS Church could be coming.

If it comes, that crisis will have its origins in the LDS Church’s complicated relationship with homosexuality. Although the church has consistently regarded homosexual activity as sinful and same-sex marriage as unacceptable, Mormon leaders have demonstrated an increasing tolerance regarding limited issues of gay rights, including support for a 2009 Salt Lake City ordinance guaranteeing housing and employment protections to gays and lesbians. The church also backed the Boy Scouts’ decision to allow gay scouts early last year. For LDS leadership, supporting certain rights for gays and lesbians does not necessitate endorsing same-sex marriage, but that distinction may seem increasingly confusing for lay Mormons. “The Family,” then, provides the clarifying reminder, disentangling same-sex marriage from the basic humanity of gays and lesbians while reinforcing heterosexual marriage as the cornerstone of Mormon salvation. And its continual reissuance underscores the LDS Church’s ultimate authority, reminding Mormons that a seeming political question has eternal consequences for all of them. It remains an open question, however, whether they will continue to agree.