The father of Republican presidential candidate Sen. Ted Cruz is warning American Christians about the "freedom of worship" espoused by the Obama administration.

Last year, the Department of Homeland Security reportedly replaced "freedom of religion" with "freedom of worship'' as a basic American right listed on the civics tests given to immigrants who want to become naturalised citizens.

WND claimed that the Obama administration has indirectly or secretly replaced the "freedom of religion'' with "freedom of worship'' in official pronouncements, which apparently contradicts the first clause of the First Amendment: "Congress shall make no law respecting the establishment of religion, or prohibiting the free exercise thereof..."

Pastor Rafael Cruz, author of the new book "A Time for Action: Empowering the Faithful to Reclaim America,'' said the subtle shift in language would be "devastating" for America if it would be backed later by new policy and practice.

"Most Christians don't realise the danger of freedom of worship," Cruz said during a recent appearance on "Hagee Hotline" with Pastor Matthew Hagee, WND reported.

"Freedom of worship is not the same as freedom of religion. Every Communist country around the world has freedom of worship. What freedom of worship means is you can worship inside a house of worship,'' Cruz said.

He explained that in his native Cuba if a person tries to spread the gospel outside the church building, he or she goes to prison. When sharing the gospel inside a church, he said there may be some spies present to ensure no one talks against the government.

"So freedom of worship is to try to keep our message of the gospel just locked up inside the four walls of the church and remove any message of Christianity from the civic society," Cruz said. "That will destroy the moral fibre of America, and that's what's happening in America today."

WND cited the case of Cynthia and Robert Gifford who, aside from going to church and worshipping God, also have the right to express their religious views on homosexuality by refusing to allow a lesbian couple to use their upstate New York farm for a wedding.

When the Giffords refused to allow Jennifer McCarthy and Melisa Erwin to hold their wedding ceremony at Liberty Ridge Farm, New York state fined them $10,000 and assessed $1,500 in damages, thus curtailing them to practice their faith, the report said.

Freedom of religion means the right to live according to one's faith, including the right to manifest one's religion or belief in practice, both in public or private without interference from the state, legal authorities say.

Under freedom of worship, however, churches can only teach the faith inside the four walls of their facilities, they add.