A leading Southern Baptist theologian and commentator is to issue a call for "faithful, biblical witness" in a book to be released next week.

The president of the Southern Baptist Theological Seminary, Rev Dr Al Mohler, reflects in We Cannot Be Silent on the legalisation of same-sex marriage, the emergence of "transgenderism" and on divorce.

Interviewed for the seminary's Southern News, Mohler said: "I am confronted daily with Christians who are asking one of the most basic questions and that is, 'How did this happen?'"

In his book, Mohler says America's Supreme Court will be held accountable by the court of "divine judgment" for legalising same-sex marriage.

In the Southern News interview, he said: "The biblical worldview explains that the fallen human reason will demonstrate itself in sinful irrationality. And even though same-sex marriage is, biblically speaking, not possible, in terms of human culture it is now possible. It was thinkable and now it's, at least in terms of a legal reality, actual. That doesn't mean, by the way, that it actually exists."

He writes in his book that the cultural acceptance of contraceptives, no-fault divorce, reproductive technologies and extramarital sex paved the way for same-sex marriage.

"Long before same-sex marriage was on the moral horizon, many of us were making clear that the divorce revolution was one of the central engines of the breakdown of marriage as an institution," Mohler said. "You can have heterosexual divorce without legalising same-sex marriage, but you really can't legalise same-sex marriage until you've passed the moral threshold of normalising divorce."

Of the "transgender revolution", he says that he predicted 20 years ago that it would be "far greater and more devastating in its effects, more potent in terms of its moral confusion, more complex when it comes to its pastoral challenge than homosexuality and even same-sex marriage". Mohler said it went "right to the heart of what it means to be human beings made in the image of God, and whether or not our bodies are part of God's intention for us and also reflect His glory and His purpose for us".

Mohler has previously criticised gay conversion therapy, saying that homosexuality cannot be turned on or off like a switch. At a conference at his seminary earlier this month he said gay people could become straight by accepting the Bible, but added that Christians had sinned against gays by "reducing a massive human struggle to simplistic explanations".

 We Cannot Be Silent will be available from October 27.