Atheist groups are unhappy with President Donald Trump for allowing a weekly Bible study to take place in the White House.

The Freedom From Religion Foundation (FFRF) said the Bible study might even be an illegal use of taxpayer funds, the Washington Times reported Thursday.

"If those officials want privacy, the solution is pretty damn simple: Study the Bible in your private capacity, not in your official capacity and at your government desk," the group said in a statement Thursday. "Do it on your time, not the taxpayers'. In short, get off your knees and get to work."

The person behind the Bible study is Ralph Drollinger, founder of Capitol Ministries. His organization has established similar programs in the House and Senate, and 40 state capitals and 24 foreign countries.

Top Trump administration officials are reported to be attending the weekly Bible study. Attorney General Jeff Sessions, Education Secretary Betsy DeVos, Energy Secretary Rick Perry, Agriculture Secretary Sonny Perdue, and CIA Director Mike Pompeo are frequent participants. Trump has yet to attend one of the studies and Vice President Mike Pence plans to attend the studies when his schedule allows.

Drollinger has already noticed the influence the Bible study has had on some administration officials. He told CBN News that Sessions will "go out the same day I teach him something, and I'll see him do it on camera, and I just think, ‘Wow, these guys are faithful, available, and teachable, and they're at Bible study every week they're in town.'"

The FFRF argues that members of the Trump administration cannot keep their religion separate from their official duties.

"Each week, these pious politicians spend their time — your time, dear taxpayer — perusing a book that condones child sacrifice, slavery, misogyny, and the subjugation of women, genocide, and eternal torture for those who believe differently," the group said. "If ever there were a book that government officials ought not to follow, it's the Bible."

The FFRF also has taken issue with Drollinger's past comments.

"That Drollinger has unfettered access to the highest levels of our government is scary and raises serious state-church concerns," the group said. "For instance, all these messages have a direct impact on public policy, including on LGBTQ rights, women's rights, the social safety net, the right to choose, environmental issues, and global climate change."

The secular organization says Drollinger's access to the White House might violate lobbying regulations and that the FFRF is investigating the matter.

"This access and ability to affect policy might run afoul of lobbying regulations, something FFRF attorneys are investigating," the group said.