Andrew Keyes, who will graduate from a picturesque Catholic college in New Hampshire on May 20, has been active in his faith as long as he can remember. So when he met members of the Knights of Columbus after enrolling at St. Anselm College, he immediately signed up. He rose through the ranks, committing himself to the Knights’ ideals of fraternity and service. When the council of his school’s chapter asked him to serve as its Grand Knight, he agreed.

Then, two months before graduation, at what should have been a time of celebration, he was told he must resign his post because of who accompanied him to a Knights of Columbus party.

“A lot of the seniors knew I was bringing my boyfriend,” Mr. Keyes told America.

The episode is the latest in a years-long struggle for colleges and universities affiliated with the church to balance support for increasingly diverse student populations while adhering to church teaching, which holds that same-sex relations are sinful, even if identifying as gay or lesbian is not.

The episode is the latest in a years-long struggle for Catholic colleges to balance support for diverse student populations while adhering to church teaching.

According to Mr. Keyes, one student took issue with his decision to bring a male date to the party and reported the incident to the Supreme Council of the Knights of Columbus in New Haven, Conn., and to Benedict Guevin, O.S.B, the chapter’s chaplain.

Father Guevin asked Mr. Keyes to resign his post, citing the possible scandal he would cause by continuing to serve in leadership. In an email to America, Father Guevin said that scandal is “an action that can lead to confusion and doubt regarding the church’s teaching.”

The decision caused a stir on the small campus, shocking some in the student body who said the college is generally supportive of L.G.B.T. students. It has also led Mr. Keyes to question his place in the church.

Last month, the University of Notre Dame in South Bend, Ind., faced backlash from L.G.B.T. students after the organization Students for Child-Oriented Policy invited Daniel C. Mattson, the author of a controversial book about forsaking homosexuality, to speak on campus. In Why I Don’t Call Myself Gay: How I Reclaimed My Sexual Reality and Found Peace, Mr. Mattson describes his failed same-sex relationship and his current commitment to chastity and adherence to church teaching.

The decision shocked some in the student body who said the college is generally supportive of L.G.B.T. students.

Some students felt that some of Mr. Mattson’s claims are unsupported by science and fail to represent recent developments in the church’s attitude toward same-sex relationships. They wrote to the campus newspaper claiming the university was being hypocritical by calling its L.G.B.T students “beloved” while restricting them from inviting speakers with opinions that do not conform to the teachings of the church.

But advocates for L.G.B.T. Catholics say progress is being made.

The St. Anselm incident “goes against the trend of Catholic higher education,” said Francis DeBernardo, the executive director of New Ways Ministry. That organization, which says it is committed to reconciliation between the L.G.B.T. community and the Catholic Church, maintains a list of “gay-friendly colleges and universities.” St. Anselm is included on that webpage.

While other challenges remain for L.G.B.T. Catholics—dozens of church employees and volunteers have been fired for reasons related to their sexual orientation in recent years—Mr. DeBernardo told America that on Catholic campuses, L.G.B.T. students report feeling supported.

The St. Anselm incident “goes against the trend of Catholic higher education,” said Francis DeBernardo.

Last month, Marquette University in Milwaukee stood behind its L.G.B.T. students when a Catholic group called for the administration to cancel a “Pride Prom” event held on campus. Crux reported that the university supported the event and issued a statement saying the U.S. bishops have “expressed that there is no room for discrimination in the Catholic Church, and we will continue to make progress through inclusivity.”

In New Hampshire, Mr. Keyes believes his case went beyond his otherwise supportive campus and that Father Guevin was pressured by the Knights of Columbus Supreme Council to ask for the resignation.

But the Supreme Council disputes this, saying in a statement to America, “It is not our practice to make a determination on someone’s Catholicity” and “the Supreme Council did not direct the local chapter to take action on this issue.” For his part, Father Guevin acknowledged in an email that he reached out to the Supreme Council and was given the choice to do nothing or to ask for Mr. Keyes’s resignation.

Mr. Keyes agreed to resign but said he was surprised at the request because of what he was able to accomplish during his tenure.

Last month, Marquette University stood behind its L.G.B.T. students when a Catholic group called for the administration to cancel a “Pride Prom.”

“We started new initiatives this year,” he said, including increasing fundraising efforts and engaging with other student organizations. He said he is most proud of recruiting 12 new Knights, “the most we’ve recruited in recent years.”

Father Guevin echoes the Knights’ statement, saying Mr. Keyes’s sexuality—he identifies as bisexual—is not the problem. He maintained that the issue was not the role of L.G.B.T. persons in the church but student leaders scandalizing others by publicly opposing Catholic teaching.

“If Mr. Keyes were gay and private about it and kept his private life private, there would be no issue,” Father Guevin told the Hilltopper, a campus newspaper.

Despite the trend toward more inclusive college campuses, St. Anselm College students say this incident shows there is still work to be done.

“It’ll take a little while to get back to the faith and the church,” Mr. Keyes said, “but I’m still holding on.”

“There’s a lot of mixed feelings about Andrew being removed,” Kelsey Warner told America. Ms. Warner, a junior, is the president and founding member of True Equality and Dignity Alliance, the college’s first L.G.B.T. student organization. “It puts Catholic L.G.B.T.Q+ people in a difficult situation,” she said.

As for the college, it says the Knights operate as an independent entity and without campus oversight.

The administration said in a statement to America that the school “has no authority over action taken by its membership, the chapter chaplain or the organization’s national office.” The school has shown support for its students in other ways, including hosting an L.G.B.T. visibility day, attended by students, faculty and the president of the college, according to Ms. Warner.

Before the party, Mr. Keyes was an altar server and master of ceremonies at the campus church. But since he was forced to step down, Mr. Keyes said he was stripped of his responsibilities and he has not been scheduled to serve at Masses. He said he finds it a little painful to attend Mass with his peers and has not felt motivated to go since the incident.

As he looks forward to life after graduation, Mr. Keyes says he will not continue to be a member of the Knights of Columbus and hopes to find more welcoming Catholic communities.

“It’ll take a little while to get back to the faith and the church,” Mr. Keyes said, “but I’m still holding on.”

Correction: May 14, 2018
This piece stated incorrectly that the administration of Notre Dame invited Daniel C. Mattson to speak on campus. The author was invited by the student organization Students for Child-Oriented Policy.

Angelo Jesus Canta is a graduate student of theology at the Boston College School of Theology and Ministry and former O’Hare Fellow at America. He studied Marian devotion in Italy and China as a Ricci Scholar at Loyola University Chicago.