The battle over gay marriage is being fought in nearly every corner of American society — from public schools to the highest courts, and from television sitcoms to neighborhood barbecues.

Religious Americans — particularly evangelical Christians — have often been at the center of these debates, attempting to hold the line on traditional understandings of marriage. But as support for same-sex marriage grows (a clear majority of Americans now favor same-sex marriage), many Christians are starting to shift. Indeed, the majority of white mainline Protestants, white Catholics, and Latino Catholics now back same-sex marriage rights. Strong majorities of white evangelical Protestants and black Protestants continue to oppose gay marriage, but there are both geographical and generational cracks in the foundation.

Many of the largest Christian publishers are coming out with books supporting same-sex relationships. More are on the way. These books have spurred praise from pro-gay Christians and strong resistance from the movement's right flank. All of this indicates that Christian publishing may be the next battleground in America's explosive debates about gay marriage.

Rewind to April when Convergent Books, a division of Crown Publishing Group, released God and the Gay Christian: The Biblical Case in Support of Same Sex Relationships by Matthew Vines. The book is an attempt by Vines, whose 2012 YouTube video claimed that "being gay is not a sin" went viral, to argue that the Bible does not condemn committed, monogamous same-sex relationships. The book's release sent many conservative Christians into panic mode.

Christopher Yuan, an author and Christian professor who claims God saved him from the "gay lifestyle," wrote a withering review of Vines' book in Christianity Today. Albert Mohler, president of Southern Baptist Theological Seminary, warned that the book sought "to overthrow two millennia of Christian moral wisdom" and released a full-length e-book to rebut Vines' arguments.

But the final hammer fell in mid-May when the National Religious Broadcasters (NRB) forced Waterbrook Multnomah Publishing Group, an evangelical publisher and the sister imprint of the one that published Vines' book, to resign its membership in the organization.

"Unfortunately, while the Multnomah Publishing Group is separate from Convergent, as a legal and business entity, the staff of the Multnomah and Convergent operations are substantially the same," wrote NRB CEO and president Jerry Johnson. "This issue comes down to NRB members producing unbiblical material, regardless of the label under which they do it."

NRB essentially not only forbade members from publishing such books, but said they can't be professionally associated with publishing imprints that do. Call it six degrees of Matthew Vines.

The question now facing NRB and similar organizations is not what they'll do with Convergent, but how they'll respond to other books from Christian publishers arguing similar positions. An increasing number of titles advocate for a rethinking, reframing, or outright reversal of the traditional Christian understanding of sexuality. To wit:

Wendy VanderWal-Gritter argues in Generous Spaciousness: Responding to Gay Christians in the Church that congregations should be open to more progressive views on sexuality. The book was released by Brazos Press, an imprint associated with the evangelical Baker Publishing Group.

James Brownson makes seminary-level arguments in Bible, Gender, Sexuality: Reframing the Church's Debate on Same-Sex Relationships to claim that the Bible allows for committed same-sex relationships. The book is becoming a staple among Christians with progressive views on sexuality and was released by the Christian academic press, Eerdmans.

Justin Lee in Torn: Rescuing the Gospel from the Gays-vs.-Christians Debate and Jay Bakker in Fall to Grace take progressive stances on the issue. Both titles were published by Jericho Books, a sister imprint to an evangelical press that publishes books by conservatives like James Dobson.

Pastor Mark Achtemeier shares why he has shifted in The Bible's 'Yes' to Same Sex Marriage: An Evangelical's Change of Heart. The Presbyterian Westminster John Knox Press released the book. Pastor Ken Wilson released a similar work, A Letter to My Congregation, with a smaller independent press.

My sources within Christian publishing tell me that many similar titles by gay Christians, professors, and pastors who have changed their positions are being acquired and developed now.

One such book is Facing the Music: Discovering Real Life, Real Love, and Real Faith by Jennifer Knapp, which is set for release in October. Knapp is a Grammy-nominated Christian musician who has come out as a lesbian. Howard Books is a Christian imprint of Simon & Schuster that also publishes the Duck Dynasty brand and many conservative evangelical authors.

Howard is not a member of NRB, but the publisher is a member of the Evangelical Christian Publishers Association (ECPA). Mark Kuyper, president and CEO of the ECPA, says no members have attempted to challenge Howard or Waterbrook Multnomah's membership. Publishing books affirming same-sex relationships would not be grounds for removal, according to Kuyper, because it would not violate the ECPA's statement of faith.

Kuyper agreed with my hunch that we're at the beginning of this trend. He told me that he expects to see more titles from Christian publishers released on both sides of the issue in the coming months and years.

"Part of what is so wonderful about publishing is that it is the marketplace of ideas," Kuyper says. "Christianity has gotten to the point where it is brave enough to publish two sides of a hot-button issue from a biblical perspective, and that's really impressive. I can't recall a time when I've ever seen this happen before, and I think it is a positive development."

We can assume that many of Kuyper's conservative Christian colleagues don't share his optimism about this trend in Christian publishing. Of course, what matters is not what the religious talking heads think, but whether the masses of pew-sitting, church-going, vote-casting Christians will be persuaded.

And mark this down: If the battle over same-sex relationships being fought among conservative Christians is won by the pro-gay advocates among them, the larger cultural war is all but over.