Mariah Walton has been battling to stay alive since birth because of a heart defect doctors say could have been fixed if her parents had simply trusted modern medicine, and now she wants her mother and father to face justice.

The 20-year-old Idaho woman can only hope for organ transplants that could save her life, even though they may do little to stem the bitterness she feels toward her parents over their hardcore fundamentalist beliefs. Walton's older sister, Emily, said their parents are Mormon, but practice beliefs out of step with the mainstream church, relying solely on prayer and rejecting medical care. Mariah Walton blames those beliefs for the fact her congenital heart defect went untreated in childhood.

“She's on some powerful medicines that are keeping her going but once they stop working she'll need a lung transplant and maybe a heart transplant.”

- Emily Walton, speaking about her sister

“She's in pain or feeling ill about one-third of the time,” Emily Walton, who lives with her sister in Boise, told FoxNews.com. “She's on some powerful medicines that are keeping her going, but once they stop working she'll need a lung transplant and maybe a heart transplant.”

The case raises questions about religious freedom and medicine, a debate that played out within the Walton family two years ago when Mariah – who had neither a birth certificate nor Social Security number – threatened her father into taking her to a doctor for the first time. She learned that she was born with a hole in her heart and was diagnosed with pulmonary hypertension and irreversible heart damage. According to medical professionals, the condition could have been corrected if treated earlier.

The revelation prompted Walton to cut off contact with her parents and call for them to be criminally prosecuted, according to The Guardian.

"Yes, I would like to see my parents prosecuted," she told the newspaper. "They deserve it -- and it might stop others."

The possibility of prosecution is remote. Under Idaho’s 1972 “Child Protective Act,” parents are immune from prosecution for any charges – including involuntary manslaughter and negligent homicide – if they depend exclusively on faith healing. The law states that “no child whose parent or guardian chooses for such child treatment by prayers through spiritual means alone shall be deemed for that reason alone to be neglected or lack parental care.”

What Mariah and Emily Walton hope they can accomplish is to raise awareness of the issue and build momentum for changing a law they believe allows children to needlessly suffer.

“I hope that people will learn that if you think something is wrong you should say something or do something even if it's scary or even if you're afraid,” Emily Walton told FoxNews.com.

Last year, a task force convened by Idaho Gov. Butch Otter raised questions about the impact religious exemptions under the 1972 law have on children, with a particular focus on a Pentecostal group known as the Followers of Christ sect. That 2,000-member group, which is based primarily in Idaho and Oregon and also rejects medical care, may be 10 times higher than the rest of the state, the task force determined.

At least 11 minors whose parents belong to the small sect have reportedly died within the past five years from a slew of mostly preventable conditions, such as respiratory failure and disease, sepsis, chronic pneumonia, severe vomiting and diarrhea, bone infections associated with leukemia and even a case of severe food poisoning that led to a ruptured esophagus and later cardiac arrest.

The Governor’s Task Force on Children at Risk's recommendation that, while “religious freedoms must be protected, vulnerable children must also be appropriately protected from unnecessary harm and death,” prompted a repeal bill. It died without so much as a hearing in the Legislature.

Five other states, Arkansas, Iowa, Louisiana, Ohio and West Virginia, also have faith-centered safeguards for felony crimes, including manslaughter. According to legal experts, the issue does indeed raise critical questions over where the line is drawn between the First Amendment, religious and parental rights, and child abuse and rights of the minors themselves.

“The U.S. Constitution requires that the government not interfere with religious practices or religious beliefs, yet this needs to be balanced with the governmental interest in protecting children,” said criminal defense attorney Anahita Sedaghatfar.

Oklahoma-based internist Dr. Larry Altshuler also told FoxNews.com that medical professionals often find themselves restricted in what treatment they can provide to children.

“In order to treat against the parent’s wishes, a court order is necessary but is often difficult to obtain due to issues of First Amendment rights,” he said.

In Oregon, where the Followers of Christ has a small following, lawmakers in 2011 repealed all religious exemptions for refusing medical care. The move followed public outcry after an 11-year-old boy died from untreated diabetes and the district attorney declined to prosecute his parents, who were members of the Followers of Christ. Just last year, the state of Washington also took steps to remove faith-based exemptions pertaining to criminal maltreatment of children and at-risk adults.

Rick Ross, author of “Cults Inside Out: How People Get In and Can Get Out,” said Followers of Christ is “socially isolated and largely monitored,” and that “members often characterize the questioning of their beliefs regarding medical care as ‘persecution.’”

Neither Followers of Christ officials nor Walton’s parents could be reached for comment. But mainstream religious leaders say it is in most cases misguided to reject medical treatment, especially when children are at risk.

“While no one wants the government regulating their religious freedoms, there must be laws to protect against any form of religion that prevents a child from receiving care when there is the likelihood of imminent danger,” said Jay Lowder, founder of Wichita Falls, Texas-based Jay Lowder Harvest Ministries.

God heals people through doctors and medicine, said the Rev. Mark Turner, pastor of Family Ministry Nansemond River Baptist Church in Suffolk, Va.

“We should see doctors and modern medicine as another gift of God that he gives to all,” Turner said. “Scripture is full of examples of people using the medicinal techniques of the day,” he said. “Christianity stands for life in all its forms. Parents cannot hide behind the pretense of religion to harm, abuse, or neglect a child.”

In the meantime, Mariah Walton, who doesn’t know if her next breath will be her last, vows to live life to the fullest. Emily – who she lives with – this week launched a GoFundMe page titled “Mariah’s Going to Paris” in a bid to boost her ailing sibling’s quality of life.

“Mariah's condition means that she misses out on many fun things that young people get to do,” Emily Walton said. “And I want to make sure that she can have some fun and we can enjoy our time together while she's feeling up to it.”