The head of the conservative group Family Research Council has accused Justin Welby, Britain's archbishop of Canterbury, of having "absolutely no grasp on the biblical foundations of his faith" but "criticizing Americans who do" after the Anglican leader claimed to not understand Christians who support President Donald Trump.

"Britain's archbishop of Canterbury is considered a 'top religious authority' -- but after his latest interview, few understand why," Tony Perkins, president of FRC, wrote in a recent op-ed. "The leader of the Church of England has absolutely no grasp on the biblical foundations of his faith, yet feels quite free criticizing Americans who do."

Perkins pointed out that in an interview over the weekend, Welby "lashed out at U.S. evangelicals for their enthusiastic support of President Trump -- seemingly clueless of all the administration has done to advance religious liberty and expression in America."

When asked about the "support from fundamentalist Christians" in America that Trump receives, Welby told ITV Preston:

"There's two things going through my mind: do I say what I think, or do I say what I should say?

"And I'm going to say what I think," Welby responded.

"No, I don't understand it. I really genuinely do not understand where that is coming from."

Perkins contended that the "feeling is mutual," as many Evangelicals who believe the Bible "were just as baffled by Welby's approval of same-sex marriage as the head of the Church of England."

"Calling them 'right and proper,' Welby also said that he couldn't 'give a straight answer' on whether homosexual behavior is a sin," Perkins asserted, quoting Welby as telling GQ, "I am having to struggle to be... faithful to Scripture."

"No kidding. As England's 'spiritual leader,' Welby ought to know better than anyone that the government can legalize a sinful act, but they can't make it morally right," Perkins said.

"Say what you will about Donald Trump, but there shouldn't be any mystery about his base's support - unless, as his statements suggest, Welby doesn't understand Christian orthodoxy," he concluded.

"Listen to Trump's campaign promises, and then look at his administration's actions. He's pursuing policies on life and religious freedom that are more consistent with biblical principles than any president in decades. In all honesty, it's a sad commentary on the state of the church when politicians take positions that are more in line with biblical truth than its so-called leaders."

Welby also told ITV he'd be willing to attend a state dinner in Trump's honor if the president came to Britain on an official visit, as part of his job is to meet with people he disagrees with "and to testify with the love of Christ to them and to seek to draw them in a different way."

"I spent years and years involved in conflict stuff around the world where I met people who had killed many, many people," he told ITV.

However, he emphasized "It'd be unlikely I'd do more than shake hands with him."