BRAINTREE -- As congress returns from recess Sept. 9, Cardinal Seán P. O'Malley is joining several of his fellow bishops in urging action on the issue of immigration reform.

The U.S. Senate passed an immigration bill in June and the U.S. House of Representatives now has the bill before it.

"This is a major question in our public life as the Congress returns to work," Cardinal O'Malley said in a letter dated Sept. 8 and distributed to all parishes.

Father J. Bryan Hehir, Secretary for Health and Social Services, said the Church in the United States and the Archdiocese of Boston hold a single, unified stance on immigration reform.

"This is a national problem that is important for the country as a whole, to find a humane and effective system. The Church in this country has high stakes in this question," Father Hehir said.

He pointed out why the archdiocese and the Church take interest in the issue on the national and local scale.

"There are two reasons why the Church in the United States and the Church in the archdiocese needs to be interested in this question, on pastoral terms and on public policy terms," he said.

Father Hehir said that immigrants make up a large portion of the Catholic community, so the pastoral interest of the Church in immigrant communities remains high.

He also pointed to the Catholic Church's interest in immigration reform as it relates to its moral teachings.

"As a Church with our social teaching, we've got basic values and principles by which we are directed to try to influence public policy on an issue that has high moral content, as this does," he said.

Father Hehir said Archbishop Jose H. Gomez of Los Angeles, chairman of the U.S. Conference of Catholic Bishops Committee on Migration, called for action and unity this summer when he commended the senate in June because it passed S. 744, the Border Security, Economic Competitiveness, and Immigration Modernization Act of 2013, by a vote of 68-32.

"This is important for the Church in the United States, it's important to us pastorally and in terms of our voice in public policy, and therefore as we come to a critical moment in how the immigration bill may or may not proceed, I think the general decision at the bishop's conference was to mobilize dioceses around the country to address it," Father Hehir said.

Father Hehir said Cardinal O'Malley has much experience to draw on for his support of immigrant communities, because the cardinal spent much of his time in the priesthood serving and interacting with immigrant communities.

"As a younger priest in Washington, he cared for, pastorally, a large community of immigrants mainly from Latin America and Central America, so his own personal history on this is significant, and his knowledge of the question is significant," Father Hehir said.

In his letter, the cardinal pointed out the historical importance of immigration issues in the life of the Church, since the early days of Catholicism in the United States up until today.

"Immigrants today come in good part from Asia and Latin America, but their needs are in many ways similar to those of our ancestors," the cardinal said.

He said Catholic social tradition and Catholic moral teaching -- rooted in the sacredness of human life, the dignity of the human person, the protection of human rights, and standards of social justice -- stands behind the position of the Church on immigration reform.

"We recognize that immigration policy is a complex question and that there are competing objectives at stake. The Church's position rests on the conviction that moral ideas about dignity and justice call for changes in the current policies," he said.

He said bishops remain focused on comprehensive immigration reform aimed at a path to citizenship for the 11 million undocumented men, women and children already in the United States.

"The status of those people -- whose lives, dignity and human rights are at stake -- is the central moral issue at this moment in the policy debates," he said.

The cardinal called for comprehensive reform of the current system.

"Without comprehensive reform it will not be possible to resolve the core issue of the undocumented; partial efforts will leave too much undone. Citizenship is also essential; legal status without a path to citizenship leaves unprotected millions of people who have lived in the shadows for far too long. Comprehensive reform should also be rooted in the principle of family unification," he said.

He said the Church reached out across the country to appeal to the largest single religious community in the nation, American Catholics.

"We invite your support; we ask you to consider carefully the case for reform. With your help the Church as a whole can help write a new chapter in the history of our nation," he said.

According to the cardinal, the Church intends to address this issue publicly.

"The Church intends to be an active participant in the immigration process. We will continue through Catholic Charities and our parishes and schools to assist new Americans as they enter our society and contribute to it, as immigrants have for centuries," he said.