Jacob Broom was a Lutheran, according to most sources. Broom devoted time to serving his church. Some sources indicate he was a Quaker and/or an Episcopalian.
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 150-151:
A well-to-do businessman and civic leader, Broom spent most of his life in the service of his hometown, Wilmington, and he was one of the more obscure signers [of the U.S. Constitution]. His most important political activity was attendance at the Constitutional Convention...
Broom also found time for philanthropic and religious activities. He served on the board of trustees of the College of Wilmington and as a lay leader at Old Swedes Church. He died at the age of 58 in 1810 while in Philadelphia and was buried there at Church Church Burial Ground.
According to Dorion, Jacob Broom was identified as a Quaker by the Library of Congress, and he was later an Episcopalian according to A History of Delaware Through its Governors 1776-1984 by Roger A. Martin. (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.