Athlete Ally, a group advocating LGBT inclusion in sports, has severed ties with tennis legend Martina Navratilova despite her longstanding advocacy for gay rights. Her crime? She disagreed with the idea that biological women should be forced to compete with biological men in sports, and especially tennis. To Athlete Ally, this constitutes heresy against transgender identity.

“Martina Navratilova’s recent comments on trans athletes are transphobic, based on a false understanding of science and data, and perpetuate dangerous myths that lead to the ongoing targeting of trans people through discriminatory laws, hateful stereotypes and disproportionate violence,” Athlete Ally said in a statement announcing they were severing ties with the openly gay tennis legend.

“As an organization dedicated to addressing root causes of homophobia and transphobia in and through sport, we will only affiliate with those committed to the same goal, and not those who further misinformation or discrimination in any way. Given this, Navratilova has been removed from our Advisory Board and as an Athlete Ally Ambassador, effective immediately,” the organization announced on Tuesday.

Navratilova has expressed alarm about the rush to allow biological men to compete with women in women’s sports. “You can’t just proclaim yourself a female and be able to compete against women,” she tweeted last December. “There must be some standards, and having a penis and competing as a woman would not fit that standard.”

While the tennis star admitted she “could have phrased it more delicately and less dogmatically,” she explained why she draws the line on this important issue in an op-ed for The Sunday Times last week.

“The rules on trans athletes reward cheats and punish the innocent,” her headline stated. “Letting men compete as women simply if they change their name and take hormones is unfair — no matter how those athletes may throw their weight around.”

“A man can decide to be female, take hormones if required by whatever sporting organization is concerned, win everything in sight and perhaps earn a small fortune, and then reverse his decision and go back to making babies if he so desires,” Navratilova wrote.

“It’s insane and it’s cheating,” the tennis legend continued. “I am happy to address a transgender woman in whatever form she prefers, but I would not be happy to compete against her. It would not be fair.”

Indeed, boys who identify as girls have been defeating biological girls in high school track and other sports in recent years. In one bizarre case, a high school boy who identifies as a girl won two girls’ state championships — as a freshman.

Rather than weighing the merits of Navratilova’s claims, Athlete Ally took offense at her stunning act of heresy. The lesbian tennis star had the gall to describe “trans women” as men who “decide to be female.” Oh, horror!

“First of all, trans women are women, period. They did not decide their gender identity any more than someone decides to be gay, or to have blue eyes,” Athlete Ally confidently declared — despite a study suggesting transgenderism among young girls is a social contagion.

Then the LGBT group made the ridiculous claim that “there is no evidence at all that the average trans woman is any bigger, stronger, or faster than the average cisgender woman, but there is evidence that often when athletes lower testosterone through hormone replacement therapy, performance goes down.”

Yes, Athlete Ally suggested that there is “no evidence at all” that biological men are, on average, “any bigger, stronger, or faster” than biological women. This is an absurd statement, laughable on its face. Even if transgender identity is taken as a person’s “true” identity, that person’s body is male or female, down to the cellular level, and biological men are, on average, stronger and faster and bigger than biological women — that’s one of the key reasons women’s sports became separate in the first place.

Athlete Ally started repeating transgender identity talking points as if explaining the finer points of a catechism.

“Trans women athletes aren’t looking to take over women’s sport. They are women, and want to compete in the sport they love, just as any other athlete would,” the LGBT group declared. “In fact, they’re largely underrepresented. Trans athletes have been allowed to openly compete in the Olympics since 2003, and yet no transgender athlete has ever gone to the Olympics. Professional trans women athletes are extremely rare.”

Many women who want to compete in sports might be glad for that fact. Lamenting the “underrepresentation” of transgender athletes is itself a controversial opinion. Many lesbians and feminists have spoken out against the transgender movement, specifically because it allows biological men to enter women’s spaces.

Athlete Ally acknowledged Navratilova as a “trailblazer for LGBTQ people in sports—someone who, like us, believed in the power of sport to advance equality, dismantle stereotypes, and build a more inclusive society.” The tennis legend joined Athlete Ally in 2011.

The LGBT group declared that Navratilova’s “latest statements stand in stark contrast to that vision, and to our core beliefs and values as an organization.” Athlete Ally dismissed criticisms of transgender identity as attempts “to dehumanize trans people,” and treats any dissent from the transgender cult as high heresy.

Americans should realize just how radical this LGBT group’s position truly is. Lesbians have opposed transgender activism for a wide variety of reasons, and biological men invading women’s spaces is often a key concern.

They have also warned that encouraging less feminine women to think of themselves as men would constitute a form of “conversion therapy,” pushing lesbians to “become” straight “men,” rather than embracing their sexuality. Worse, lesbians are often encouraged to be sexually open to “transgender women,” even men with penises. For this reason, some consider the transgender movement a form of “rape culture.”

Importantly, Athlete Ally concluded with a powerful statement: “The LGBTQ community is not a monolith.” As more and more lesbians and feminists stand up for women’s rights against the invasion of biological men into women’s spaces, that will become even more clear.

Follow Tyler O’Neil, the author of this article, on Twitter at @Tyler2ONeil.