Thompson is a Roman Catholic, but is pro-choice. In May 2004, he, along with 47 other Catholic Democratic Congressmembers, sent a letter to Cardinal Theodore McCarrick of Washington, D.C. to dissuade him from refusing to administer Holy Communion to Catholic Congressmembers who practice pro-choice legislative voting. In February 2006, he was one of 55 Democratic U.S. Representatives identifying as Catholic who signed a "Statement of Principles" which affirmed a commitment to their faith but acknowledged opposition to Catholic doctrine on some issues. They stated that on those issues, such as abortion rights, they would follow their conscience instead of the church's teachings. In response, the U.S. Catholic Bishops issued a "Statement on Responsibilities of Catholics in Public Life" that said, in part, "Catholic teaching calls all Catholics to work actively to restrain, restrict and bring to an end the destruction of unborn human life."