Have you even read the Bible? Fox pundit warns of polygamy if marriage laws aren't based on 'scripture'

Fox News contributor Cal Thomas argued over the weekend that polygamy and "adult-child marriage" could become legal in the United States unless the Supreme Court bases its same-sex marriage ruling on "scripture."

Speaking to Fox News host Shannon Bream on Sunday, Thomas asserted that a Supreme Court ruling in favor of marriage equality would mean that evangelical pastors who openly preach against gay rights could be prosecuted.

"Even during the anti-slavery movement, even the pro-slavery movement in the South in the United States, the United States government didn't come in and try to keep pastors from preaching either for or against slavery," he insisted. "They let them have freedom of speech. You hear a lot from the left about the separation of church and state. A lot of evangelicals would would be happy if the state got back on its side of the line."

Same-sex marriage was likely inevitable, meaning there would be a "slippery slope" to polygamy and adults marrying children if the court did not set strict limits, according to Thomas.

"If equal protection covers gays, lesbians, transgenders and the rest, what about the polygamists?" Thomas asked. "And even further out, the adult-child marriage people, men especially, who want to marry young boys or young girls -- as occurs in some Muslim countries, by the way -- they want their rights too."

"So, who's going to say no? And based on what?" he continued. "Where's the standard. If it's not the Constitution, if it's not scripture, where is the standard?"

"If you are going to repeal something that has been part of human history for thousands of years, what's the new standard? And according to whom?"

Both polygamy and child marriage were accepted practices in the Bible. Some accounts even claim that Jesus' mother, Mary, was as young as 12 years old when she married Joseph, who was said to be in his thirties or forties.

Watch the video below from Fox News, broadcast June 14, 2015.