The legalization of same-sex marriage would be a “very dangerous place” for America to go and could lead to civil disobedience, former Arkansas Governor Mike Huckabee warns.

I have received an exclusive copy of a letter the Republican presidential candidate is sending to conservative leaders and pro-family activists around the nation.

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In that letter, which you can read here, he vows to “fight to defend religious liberty at all costs.”

“I refuse to sit silently as politically driven interest groups threaten the foundation of religious liberty, criminalize Christianity, and demand that Americans abandon Biblical principles of natural marriage,” Huckabee wrote.

Huckabee also had a stern message for his fellow Republican contenders – urging them to join the fight to defend the Constitution.

“If you lack the backbone to reject judicial tyranny and fight for religious liberty, you have no business serving our nation as President of the United States,” he wrote.

Huckabee has mobilized an impressive group of conservative and religious leaders – many of whom signed his letter – including National Religious Broadcasters President Jerry Johnson, Dr. James Dobson, Tim and Donald Wildmon of American Family Association, Steve Strang of Charisma Media and Mat Staver, chairman of Liberty Counsel.

“This is not just about marriage,” Huckabee told me in a telephone interview. “This is about whether or not a government can begin to put limitations on the conscious and convictions of people who have faith.”

Penny Nance, the president of Concerned Women for America, signed Huckabee’s letter. She said it’s “absolutely essential for Christians to stand and be counted.

“We strongly believe people of faith have to step forward and make a commitment,” she told me. “We fear God more than we fear man and I think that’s what Governor Huckabee is trying to say.”

Nance predicted that the legalization of gay marriage would lead to greater attacks on Christian Americans.

“We will see people of faith lose their jobs, pastors will be sued, churches will lose their tax exempt status,” she said. “Now is the time for us to speak up. We must obey God. We are not willing to bend one knee to man.”

That was the message sent earlier this week by the Southern Baptist Convention. Members passed a resolution opposing gay marriage and President Ronnie Floyd delivered a fiery declaration.

“The Supreme Court of the United States is not the final authority nor is the culture itself,” said the elected leader of the nation’s largest non-Catholic denomination. “The Bible is God’s final authority about marriage and on this book we stand.”

Huckabee said he was proud of Floyd’s stand and called his comments bold.

“When an individual is faced with a decision of bowing to Caesar or bowing his knee to God – he has to take his stand and get on his knees to God instead of Caesar,” Huckabee told me. “This is where we are rapidly heading.”

A direction that a growing number of Christians believe will lead them to engage in acts of civil disobedience.

“That does mean civil disobedience,” Huckabee told me. “It means we are obedient to a power that is not only higher than the current government, but a power that was the basis of our government.”

Huckabee said taking a stand comes with a price. He said some Christians might lose their jobs or their businesses or face lawsuits or government investigations.

“People are going to have to begin to be willing to lose things in order to preserve the country and their freedoms,” he said. “When people are told by their government what they can and can’t say, it’s one step away from being told what they can and can’t do. All other liberties begin to erode.”

Huckabee is a modern-day voice crying in the political wilderness. Religious liberty is under attack but many politicians have remained silent – fearful of the Republican Party’s powerful donor class.

It is refreshing to see a man practice what he preaches – a man willing to speak the truth regardless of the consequences.

Americans should pay heed to what Huckabee says. If generations of long-cherished traditions and convictions can be pushed aside by a small but vocal minority – then religious liberty will indeed be lost. And with it – the foundation of all our freedoms.

Todd Starnes is host of Fox News & Commentary, heard on hundreds of radio stations. His latest book is "God Less America: Real Stories From the Front Lines of the Attack on Traditional Values." Follow Todd on Twitter@ToddStarnes and find him on Facebook.