Religious perspectives on human biotechnologies vary widely, depending in part on the specific technology or application. Most religious leaders are in step with public sentiment in opposing human inheritable genetic modification and reproductive cloning, and recognize social and ethical as well as theological objections to them. In 1983, a coalition of U.S. religious leaders issued a letter to Congress calling for a ban on inheritable genetic modification. Religious communities are more divided about research involving human embryos, with many conservative Christian denominations opposing embryonic stem cell research. Communities of faith may ground their approach to human biotechnologies in theological beliefs, but their concerns also shed important light on the potential for human biotechnologies to redefine our understandings of life itself.