"If the Word of God isn't worth fighting for, I don't know anything that is."

Rowan County, Kentucky Clerk Kim Davis made this statement a day before she was locked up in prison on Thursday after a district judge found her in contempt for defying legal orders for her to desist from withholding the issuance of marriage licences to gay couples.

Interviewed by Decision magazine, Davis said she knew full well the consequences of her action. "I have weighed the cost," she said. "It's definitely no place that I thought I would ever find myself, and it is definitely out of my comfort zone."

She affirmed that issuing the licence would violate her deeply held religious beliefs that marriage should only be between a man and a woman.

"Those licences leave my office through my authority," she said. "I cannot be party to that. I just can't. If the Word of God isn't worth fighting for, I don't know anything that is."

"I cannot be separated from what I believe. I have to love the Lord with my whole heart, mind, body and soul—with every ounce of strength and might that I have in me. It's every breath we take and every beat of our heart," she tearfully said.

Despite the physical threats and mounting criticisms she's getting, Davis said "it is through God and His grace and strength that I stand, that I can have a smile on my face."

She said to her, the same-sex marriage controversy "is a Heaven or Hell issue."

She said last January, she wrote legislators in anticipation of the US Supreme Court ruling against her appeal for a stay of a federal appeals court order for her to resume the issuance of marriage certificates to all qualified applicants.

"I urged and beseeched them to get legislation on the floor while we still had time to protect clerks who had religions objections to same-sex marriage," she said. "I got only one response, and nothing happened."

Despite the Supreme Court's rejection of her plea, Davis said she will stand her ground because she cannot separate her conscience from her job which, she said, she will not give up.

Davis' attorney, Liberty Counsel's Mat Staver, said his client "is being treated as a criminal because she cannot violate her conscience. While she may be behind bars for now, Kim Davis is a free woman. Her conscience remains unshackled."

Staver said he has asked the courts and Kentucky Gov. Steve Beshear to accommodate her religious beliefs, including removing her name from the marriage licences, making the capitol the processing centre and going to online application process. But so far no action has been taken on this regard, he said.

Critics have scored Davis for refusing to issue marriage license to same-sex couples when she herself had divorced three times and gave birth to twins out of wedlock.

But Davis said she only accepted God in 2011. "The pastor preached out of Galatians, and it really stirred my heart," Davis said. "I repented right there on the altar, just fell on my knees and face and cried."

After she was jailed, her office started issuing marriage licenses. Her deputy clerk, Brian Mason, issued four licenses Friday. Five of the deputy clerks told US District Judge David Bunning that they would issue licenses.

Davis' attorneys said the licenses are illegal since they were issued without her authority.

"They are not being issued under the authority of the Rowan County clerk's office. They are not worth the paper that they are written on," Staver said.

Bunning said it's up to the couples to test whether their license is legal.