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A secular group tore into Kansas Gov. Sam Brownback over the weekend for promoting a national faith rally, saying the Republican governor needs to "repent" for allegedly violating the separation of church and state.

Whether any constitutional boundaries were actually breached is unclear, but Americans United for Separation of Church and State was unsparing in its criticism of the governor.

"The people of Kansas do not need politicians telling us when, how or whether to pray," Vickie Sandell Stangl, president of the Great Plains Chapter of Americans United, said in a statement.

"If anybody needs to repent, it's Gov. Brownback. He needs to repent for violating the constitutional separation of church and state."

The Kansas governor spoke on Saturday at a ReignDown USA event in Topeka, Kan., where he used his 10-minute appearance to discuss how he turned to religion after being diagnosed with cancer in 1995.

According to an account in The Topeka Capital-Journal, Brownback said: "I finally reached up and said, 'God, this life's yours.' It started a great adventure."

But what really rankled Americans United for Separation of Church and State was Brownback's earlier promotion of the prayer rally, in the form of a state proclamation.

"The governor is really overstepping his constitutional bounds. He was elected to serve as governor of our state, not our state pastor-in-chief," Stangl said.

Reached for comment, Executive Director Barry Lynn explained that the group was more concerned with a proclamation put out by the governor's office than his actual remarks at the event.

In the proclamation, Brownback declared Saturday -- the day of the event -- to be a "Day of Restoration."

"We collectively repent of distancing ourselves from God and ask for His mercy on us," the proclamation said.

Brownback, though, also used the proclamation to quote former American presidents -- including George Washington, Abraham Lincoln and Thomas Jefferson -- who discussed their faith and God.

"WHEREAS, our Nation's greatest leaders have called on a merciful God for favor during troubled times," the proclamation said, quoting the Jefferson line: "I tremble for my country when I reflect that God is just; that his justice cannot sleep forever."

Lynn said the proclamation went too far by "proclaiming that this is good for everyone in the state of Kansas." He said the statement was tantamount to making the ReignDown USA rally a "special state event."

The group also accused ReignDown USA organizers of wanting "government leaders to adopt their religious vision and impose it on us all."

Those organizers, though, rejected that claim.

"We were all just gathering, uniting together, and praying for change," said Shawn-Marie Cole, chief visionary officer with the organizer.

Walt Kallestad, president of the group's advisory board, said the event is not about imposing belief sets.

"ReignDown is really a call for humility, prayer, repentance," he said.

It's hardly the first time Brownback has worn his faith on his sleeves.

In August 2011, he joined Texas Gov. Rick Perry for a national prayer rally. It came as Perry was considering a run for the Republican presidential nomination.

“It is no secret that Governor Brownback is a man of faith. He believes strongly in the power of prayer and so do the people of Kansas," spokeswoman Sherriene Jones-Sontag said in the governor's defense.

Organizers for ReignDown USA have not yet returned requests from FoxNews.com for comment.