Roman Catholic and conservative Protestant leaders condemned the first reported cloning of a human embryo, while other Christian and Reform Jewish leaders supported using the procedure to cure diseases.
Cardinal Theodore McCarrick of the Catholic Archdiocese of Washington said Massachusetts scientists who recently announced that they had cloned a six-cell embryo were playing God and reducing humans to spare parts.
"While we must encourage the scientific community to continue cutting-edge research, it must occur within ethical boundaries that respect all human life," he said. Catholic teaching holds that life begins at conception, and a statement last week from the Vatican reiterated that belief.
The Southern Baptist Convention, the nation's largest Protestant denomination, and the United Methodist Church, President Bush's denomination, both urged federal lawmakers to ban the research.
The Presbyterian Church (U.S.A.) and Reform Jewish leaders took a different position, supporting cloning to cure diseases but opposing it for reproductive purposes.
Jewish authorities teach that the primary responsibility is saving human life, even if some religious laws are broken, said Rabbi Richard Address, who oversees the bioethics program of the Union of American Hebrew Congregations.
It wasn't clear whether the cloned embryo that Worcester, Mass.-based Advanced Cell Technology announced it had created would have been capable of growing into a human being. The embryo died before any stem cells were produced.