Mattson stressed the need for a "call to conversion" and to remember, "we can never be more compassionate than Jesus." He also warned against "the willful refusal to speak about the health damages of living out a life of active homosexuality, particularly among men."
"In nearly every area of both mental and physical health, the LGBT community suffers more profoundly than their heterosexual counterparts," he said.
At least 60 groups from around the world are backing the Equal Future campaign. These include secular groups such as the Human Rights Campaign, GLAAD, GLSEN, Music4Children.org, and ALL OUT.
The Global Network of Rainbow Catholics, the U.S.-based New Ways Ministry, and Dignity USA are also named as backers of the project. Catholic authorities including the late Cardinal Francis George of Chicago have rejected New Ways Ministry's self-identification as a Catholic group.
The director of the Equal Future campaign is Tiernan Brady of Ireland, who was director of the successful referenda in Ireland and Australia to give legal recognition to gay marriage. He told the Financial Times that his campaign targeting the Catholic Church will draw on practices from the Irish and Australian campaigns.
"I think one of the things we've found in all these campaigns is we can talk about rights all we want, but it's human stories that people understand and that appeal to people's humanity," Brady said.
He said the initial inclusion of same-sex couples' photos in literature for the World Meeting of Families suggested that there was already sympathy for such couples at the Vatican, even though the photos were later removed. Brady argued the Church will end up campaigning "against the sons and daughters of the men and women in your pews," and churchgoers won't understand it.
For Schneible, it is important to let each person tell their story.
"But we do not stop there," she said. "As Catholic Christians, we believe that we must always seek to understand our own stories in light of the Gospel, the story of salvation"
The wider discussion often ignores people who have same-sex attractions and embrace chastity, she said.
"Too often they are dismissed by members of the LGBT community as being dishonest, or self-hating, or deluded," Schneible continued. "On the contrary, these courageous men and women testify that, as much happiness and pleasure as they seemed to have when they were pursuing same sex relationships, they have found a deeper joy, peace and freedom by embracing the call to chastity. They make many sacrifices in order to remain faithful, but many of them speak of the closeness they have found with Christ as they walk this path to holiness."
(Story continues below)
Subscribe to our daily newsletter
One backer of the Equal Future campaign, Dignity USA, has taken several six figure grants from Jon Stryker's Arcus Foundation to support the Equally Blessed Coalition, which includes New Ways Ministry. A 2014 grant targeted the Synod on the Family and World Youth Day, aiming "to support pro-LGBT faith advocates to influence and counter the narrative of the Catholic Church and its ultra-conservative affiliates."
The foundation has given more than $390,000 to the European Forum of LGBT Christian Groups for several activities, including advocacy related to the Synod on the Family. These activities include the forum's response to "homophobic Catholic church family synod decisions" and efforts to "pursue its successful strategy of shifting traditional views." The grants also fund the drafting, testing, and use of "a counter-narrative to traditional values," according to the forum's annual report and grant announcements from the U.S.-based foundation.
The foundation is also a grant maker to the Catholics United Education Fund, Catholics for Choice, and the Center for American Progress. It funded groups in ecclesial communities, including Episcopalian groups amid the breakup of the Anglican Communion over issues such as ecclesial authority and homosexuality.
The working document for the 2018 synod discusses increasing cultural instability and violent conflicts, but also that many young people, both inside and outside of the Church, are divided when it comes to topics related to sexuality, the role of women, and the need to be more welcoming to members of the LGBT community.
The document only briefly addresses the issue of homosexuality and related topics, saying that some LGBT youth who offered contributions to the synod's general secretariat said they want to experience "greater closeness and greater care on the part of the Church."
In their responses, bishops' conferences also questioned how to respond to young people who have chosen to live a homosexual lifestyle, but who also want "to be close to the Church."