Army secretary nominee Mark Green is being scrutinized for a 2015 speech in which he said his work as a doctor had led him to believe evolution was unproven.

The former Army doctor told attendees at a church event in Cincinnati that he believed in the Bible's account of how the Earth was created.

"The evolutionists have their bad argument, too," Green said. "They say, 'Well, I can't explain how it went from this to incredibly complex, so it must have been billions of years.' That's kind of where they put their faith. The truth of the matter is — is the second law of thermo-fluid dynamics says that the world progresses from order to disorder not disorder to order.

"If you put a lawn mower out in your yard and a hundred years come back, it's rusted and falling apart. You can't put parts out there and a hundred years later it's gonna come back together. That is a violation of a law of thermodynamics. A physical law that exists in the universe," Green added, according to a CNN report published Monday evening.

The National Academy of Sciences said the theory of evolution "is supported by so many observations and confirming experiments that scientists are confident that the basic components of the theory will not be overturned by new evidence."

Green serves as a Tennessee state senator and has yet to be confirmed by the Senate.

"Irreducible complexity is important in the argument for the creationist because of this: Evolution assumes a series of minuscule changes over time, and each change has to give a survival advantage to the organism. If it doesn't, and it causes a disadvantage the organism dies and evolution ends," Green said.

The revelation came the same day that Rep. Steny Hoyer, D-Md., and House Democratic whip, said Green's nomination should be withdrawn over comments he has made regarding gay rights and Islam.

Transgender U.S. Olympian Caitlyn Jenner, a Republican voter, has said she is unhappy with Green because he does not support progressive reforms for lesbian, gay, bisexual and transgender people.

"I'm really concerned with, kind of the next move for the Trump administration, is Mark Green, who's a Republican from Tennessee, uh, senator and he's up for secretary of the Army. He's made some of the most anti-LGBT statements ever — calling me, a trans person, as a disease. I have to tell Mark Green, I don't have a disease, OK?" Jenner told Fox News host Tucker Carlson last week.

The 52-year-old physician created AlignMD, an emergency room management firm. He joined the state senate in early 2013 and also serves as chaplain of the Tennessee Senate GOP Caucus.

Green and Vincent Viola, Trump's previous nominee, both graduated from West Point. Viola withdrew his name for the position on March 2, citing an inability to separate his private financial investments from his work as a government official.