A Christian baker from Mississippi has criticised the State's new 'religious freedom' bill for "decriminilising discrimination" against LGBT people.

Govenor Phil Bryant signed a bill into law on Monday that allows religious organisations, individuals and businesses to refuse to serve lesbian, gay, bisexual and transgender people if they believe it violates "sincerely held religious beliefs or moral convictions".

It has been widely criticised as tantamount to Mississippi legalising support for discrimination against LGBT people.

Mitchell Moore, a Republican voting Christian who owns Campbell's Bakery in Jackson, told NPR that this law goes against Christian principles.

"I don't think that there is such a thing as a deeply held religious belief that you should not serve people," said Moore.

"I am here to bake cakes and to sell those cakes. I'm not here to decide arbitrarily who deserves my cake and who doesn't. That's not what I do. That's not my job.

"So leaving aside the stupidity of passing it because it decriminalizes discrimination – which, that really is kind of the biggest issue – but I can actually say I think the law of unintended consequences is going to come back to bite the people who signed this bill," he said.

"If it is my sincerely held religious belief that I shouldn't serve them, then I can do that. And I can hide behind that language. But that language is so vague it opens a Pandora's box. And you can't shut it again."

Moore, who described himself as a "deeply Christian man", said the premise of the law is counter to his belief system.

"There is no sincerely held religious belief to think that I am better than other people – to think that my sin is different than other people," he said.