A renowned public health expert who also serves as a lay minister for the Seventh Day Adventist Church has filed a lawsuit against the Department of Public Health of Georgia, accusing state officials of firing him over his religious convictions.

Dr. Eric Walsh accepted a position as the director of Georgia Department of Public Health for northwest part in May 2014. A week later, state officials requested copies of sermons he had preached as a lay minister, with topics that included following God, having compassion on the poor, health, marriage, sexuality, world religions, science and creationism among others, CBN News reports.

The day after Dr. Walsh provided copies of the sermons to the state, government officials reportedly informed him in an email that he had been fired.

"Dr. Walsh was terminated because of something he said in a sermon,'' Jeremy Dys, senior counsel for First Liberty Institute, told the Daily Signal. "No one should be fired for something they say in their sermon.''

"No one should be removed from his job for simply expressing his religious belief. In America, it is against the law to fire an employee for expressing his religious beliefs – especially when that expression takes place in a church setting,'' added Andrew Coffman, Walsh's attorney from the group First Liberty.

In May 2014, the Los Angeles Times reported that Georgia health officials retracted a job offer to Walsh "who had come under fire for controversial remarks he made on homosexuality and evolution.''

But a recording of the voicemail from Georgia officials—after they forgot to hang up their phones—captured the audio of them laughing about firing him, saying, among other things, "There's no warm way to say it—'you're out.'"

"I couldn't believe they fired me because of things I talked about in my sermons," said Dr. Walsh. "It was devastating. I have been unable to get a job in public health since then."

First Liberty Institute, a legal organisation that defends the religious freedom of Americans, represented Walsh in the case. They filed the lawsuit in the U.S District Court for the Northern District of Georgia.

Walsh has multiple advanced degrees and served on President Obama's Presidential Advisory Council on HIV/AIDs, reports say.

Reacting to Walsh's case, Roger Severino, director of The Heritage Foundation's DeVos Center for Religion and Civil Society, said: "Bureaucrats cannot deny qualified people of faith government jobs simply because they express their beliefs especially in a house of worship. If the First Amendment means anything, it's that government bureaucrats have no business acting as sermon review boards. That would be religious discrimination pure and simple."