Eight-year-old Blake Collie was at the swimming pool when he got a frightening headache. His parents rushed him to the emergency room only to learn he had a brain aneurysm. Blake spent nearly two months in the hospital.

His family did not have traditional health insurance. “We could not afford it,” said his father, Mark Collie, a photographer in Washington, N.C.

Instead, they pay about $530 a month through a Christian health cost-sharing organization to pay members’ medical bills. But the group capped payments for members at $250,000, almost certainly far less than the final tally of Blake’s mounting medical bills.

“Just trust God,” the nonprofit group, Samaritan Ministries, in Peoria, Ill., said in a statement about its coverage, and advises its members that “there is no coverage, no guarantee of payment.”

More than 1 million Americans, struggling to cope with the rising cost of health insurance, have joined such groups, attracted by prices that are far lower than the premiums for policies that must meet strict requirements, like guaranteed coverage for pre-existing conditions, established by the Affordable Care Act.

These Christian nonprofit groups offer far lower rates because they are not classified as insurance and are under no legal obligation to pay medical claims. They generally decline to cover people with pre-existing illnesses. They can set limits on how much their members will pay, and they can refuse to cover treatments for specialties like mental health.

“Nothing is guaranteed,” said Dr. Carolyn McClanahan, a physician who is also a financial planner in Jacksonville, Fla. “You have to depend on the largesse of the program.”

The main requirement for membership is adherence to a Christian lifestyle. And the alternative sharing plans keep flourishing, especially now that the Trump administration has relaxed rules to permit alternatives to the ACA.

But some state regulators are beginning to question some of the ministries’ aggressive marketing tactics, often using call centers, and said that in some cases people who joined them were misled or did not understand how little coverage they would receive if they or a family member had a catastrophic illness.

Because the groups are not considered insurance, they operate with no government oversight. “Regulators haven’t been willing to assert any control or regulatory authority over these plans,” said Katie Keith, a consumer representative to the National Association of Insurance Commissioners. “They feel their hands are tied. At the end of the day, it’s not insurance.”

But cost-share ministries have become particularly attractive to people like the Collie family who can’t afford an ACA plan. Even though premiums in the ACA market have stabilized, critics of the law insist people need alternatives.

Others complain the ministries can be vague about coverage. Greg Snider and his wife joined Florida-based Medi-Share, the program offered by Christian Care Ministry.

Snider’s wife underwent surgery last year for an abnormal heart rhythm. “After the procedure, the bills start rolling in,” Snider said, including $177,000 for the surgery alone.

Snider says Medi-Share urged him to plead with the hospital after determining he would owe more than $100,000. He said he had assumed the $800 a month he paid into a pool would help cover the expenses. After he tweeted his frustrations, the ministry told him that he would owe only $1,500 for the surgery because the hospital had forgiven the rest, he said. He now owes thousands of dollars in related medical bills and is unsure of their status.

If Medi-Share decides not to pay, Snider knows he has little recourse: “It is completely and solely up to them.”

Medi-Share says over 80% of the $774 million it collected last year went to members’ medical bills. “We take great care to ensure prospective members understand … what is eligible for sharing,” it said.