Thomas Fitzsimons was also a U.S. Representative in the First U.S. Federal Congress (1789-1791).
Thomas Fitzsimons was a devout Catholic.
From: Robert G. Ferris (editor), Signers of the Constitution: Historic Places Commemorating the Signing of the Constitution, published by the United States Department of the Interior, National Park Service: Washington, D.C. (revised edition 1976), pages 163-164:
Fitzsimons, one of several foreign-born signers and one of two Roman Catholics, was a fervent Revolutionary and later a zealous supporter of the Federalist Party... Fitzimons (FitzSimons; Fitzsimmons) was born in Ireland in 1741... Fitzsimons never ceased his philanthropy. He was an outstanding supporter of Philadelphia's St. Augustine's Roman Catholic Church. He also strived to improve public education in the Commonwealth and serve as trustee of the University of Pennsylvania.
Fitzimons died at Philadelphia in 1811 after seven decades of life. His tomb is there in the graveyard at St. Mary's Roman Catholic Church, which is in present Independence National Historical Park.
He was identified as a Catholic by: the Library of Congress and A Worthy Company: Brief Lives of the Framers of the United States Constitution, written by M. E. Bradford. (Source: Ian Dorion, "Table of the Religious Affiliations of American Founders", 1997).
Note that numerous sources and authoritative references have been consulted in order to ascertain the religious affiliation of the American Founding Fathers. Note that the excerpts and references mentioned on this page are not the only references used in order to identify this person's religious affiliation.