St. Philip’s College in San Antonio, Texas reportedly fired one of its biology professors for teaching his students that sex was determined by X and Y chromosomes.

According to Fox News, First Liberty Institute, a law firm that defends religious liberty for Americans, sent a letter to the community college on behalf of the professor, Dr. Johnson Varkey, demanding the institution reinstate him after he was fired in January 2023.

“When teaching the human reproductive system, Dr. Varkey also stated that human sex is determined by chromosomes X and Y, and that reproduction must occur between a male and a female to continue the human species,” First Liberty stated in its letter.

“In the course of teaching Human Anatomy and Physiology, he made these statements in every class for 20 years, without any incident or complaint.”

On November 28, 2022, four of Varkey’s students walked out of this class when he stated that sex was determined by X and Y chromosomes just as he had dozens of times before.

Complaints against Varkey said he has engaged in “religious preaching, discriminatory comments about homosexuals and transgender individuals, anti-abortion rhetoric, and misogynistic banter” and that his teaching “pushed beyond the bounds of academic freedom with [his] personal opinions that were offensive to many individuals in the classroom,” according to the letter.

Despite the fact that Dr. Varkey taught from a school-approved and science-based curriculum, St. Philip’s College claims his teaching was religious.

First Liberty argued his teachings are supported by his education and experience in his field, as well as his religious beliefs, but “throughout his employment, he never discussed with any student his personal views—religious or otherwise—on human gender or sexuality.”

As an adjunct professor, Dr. Varkey taught Human Anatomy and Physiology at St. Philip’s College to more than 1,500 students for 22 years, where he taught the same principles he was fired for this year, according to First Liberty.