The church wants its members to sign a pledge to support a campaign by the Canadian Health Coalition, which is lobbying the federal government to sign a new agreement with the provinces to improve the public health system.
Right Rev. Gary Paterson, moderator of the church, said Canadians shouldn't take medicare for granted.
"I am really concerned as a Christian and a church leader that health care is crucial for our population," Paterson said Tuesday in Edmonton.
"I am just wanting to enable people to think seriously about this and really let our government know that we are concerned."
The pledge says access to quality health care must be based on need, not ability to pay, and that medicare should be improved for everyone instead of expanding private for profit-services.
In 2004, the federal government announced a 10-year plan and funding commitment to improve medicare, with the aim to make timely access to quality care a reality for all Canadians.
The agreement reached with the provinces said access to medically necessary health services should be based on need, not ability to pay.
The coalition of health workers, unions, churches, seniors and anti-poverty groups said the federal government has not committed to signing a new agreement.
The groups are planning rallies across Canada Monday to press for a new national health standards accord.
Coalition executive director Michael McBane said they are planning a cross-country tour of eight cities next month to gather support.
The coalition has also requested to meet with each of the federal party leaders in May to report their findings.
"We are sounding the alarm to alert Canadians to the fact that the Harper government is not providing federal leadership in health care," McBane said from Ottawa.
"This will lead to a fragmentation of services across the country and access to care will depend on where you live and your ability to pay."
Paterson said he expects the call for action will create some buzz in the church's 3,075 congregations, but noted the United Church, which is a member of the coalition, has supported universal health care for 60 years.
He said it will be up to church ministers and people in individual congregations to decide how to respond.
Paterson said the church is being political in the sense that health care is an important social issue, but it is not endorsing any one political party.
"Here is a place to be involved," he said. "Here is a chance to share your faith in the broader political realm."
The United Church is Canada's largest Protestant denomination, with 463,879 people who are members of congregations.
In 2011, Statistics Canada said more than two million Canadians identified their religion as United.
Some of the national organizations in the coalition include the Pensioners Federation, Council of Canadians, Canadian Doctors for Medicare, Canadian Federation of Nurses Unions and the Canadian Labour Congress.