(CNN) In a pair of 2015 speeches, President Donald Trump's nominee for a federal judgeship in Texas described transgender children as evidence of "Satan's plan," lamented that states were banning conversion therapy and argued that sanctioning same-sex marriage would lead to polygamy and bestiality.

Jeff Mateer, the current first assistant attorney general of Texas, was serving at the time as general counsel of the First Liberty Institute, a religious liberty advocacy group known before 2016 as the Liberty Institute. He faced criticism from LGBT rights groups for his work with the organization, such as opposing the expansion of nondiscrimination protections to LGBT people in the city of Plano. If confirmed by the US Senate, he will serve on the US District Court for the Eastern District of Texas.

In a May 2015 speech , titled "The Church and Homosexuality," Mateer discussed a Colorado lawsuit in which the parents of a transgender girl sued her school for preventing her from using the bathroom of her choice.

"In Colorado, a public school has been sued because a first grader and I forget the sex, she's a girl who thinks she's a boy or a boy who thinks she's a girl, it's probably that, a boy who thinks she's a girl," Mateer said in a video posted on Vimeo in 2015 and reviewed by CNN's KFile. "And the school said, 'Well, she's not using the girl's restroom.' And so she has now sued to have a right to go in. Now, I submit to you, a parent of three children who are now young adults, a first grader really knows what their sexual identity? I mean it just really shows you how Satan's plan is working and the destruction that's going on."

Mateer's nomination comes as the Trump administration has unveiled a series of actions aimed at rolling back advancements for gay and transgender rights. Trump vowed to fight for the LGBT community during his presidential campaign and said last April that people should "use the bathroom they feel is appropriate." Since taking office, however, Trump has withdrawn an Obama administration directive that allowed transgender students in public schools to use the bathroom of their choice and issued a directive banning transgender military recruits.

In that same May 2015 speech, Mateer said that the Supreme Court decision allowing same-sex marriage could lead to what he called "disgusting" new forms of matrimony.

"I submit to you that there'll be no line there," he said. "And actually in the arguments Chief Justice Roberts, who's in the center there said, I mean, what is the limiting? Why couldn't four 4 people wanna get married? Why not one man and three women? Or three women and one man? And we're gonna spare you some of those slides. We actually have a presentation that we get into it. And I'll tell you, we say it's PG-13, it may be R, or what do they call the next one? NC-17 or whatever?"

He continued, "I mean, it's disgusting. I've learned words I didn't know. I mean, other than...my assistants here, have you ever heard the word 'throuple'?'Throuple' so that's three people coming together of different sexes, maybe mixed sexes. Them coming together. There are people who marry themselves. Somebody wanted to marry a tree. People marrying their pets. It's just like -- you know, you read the New Testament and you read about all the things and you think, 'Oh, that's not going on in our community.' Oh yes it is. We're back to that time where debauchery rules."

Later that year in November 2015, Mateer lamented that states were banning gay conversion therapy at a conference hosted by controversial pastor Kevin Swanson, who preaches that the Biblical punishment for homosexuality is death.

"Biblical counselors and therapists, we've seen cases in New Jersey and in California where folks have gotten in trouble because they gave biblical counseling and, you know, the issue is always, it's same sex," Mateer says in audio obtained by CNN's KFile. "And if you're giving conversion therapy, that's been outlawed in at least two states and then in some local areas. So they're invading that area."

Groups like the American Psychiatric Association and the American Pediatric Association have condemned the practice as having no scientific basis and the potential to do mental harm.

Mateer did not respond to a request for comment. A Department of Justice spokesperson declined to comment on Mateer's remarks.