Benjamin Rush was a Presbyterian and a devout Christian.
He was identified as a Presbyterian by the Presbyterian Historical Society and the Presbyterian Church, USA. (Source: Ian Dorion, "Table of the Religious Affiliations of American Founders", 1997).
From: B. J. Lossing, Signers of the Declaration of Independence, George F. Cooledge & Brother: New York (1848) [reprinted in Lives of the Signers of the Declaration of Independence, WallBuilder Press: Aledo, Texas (1995)], pages 99-103:
Doctor Benjamin Rush was born at Berberry, about twelve miles northeast of Philadelphia... 1745. He was descended from an officer of that name in Cromwell's army, who, after the death of the Protector, emigrated to America, and settled in Pennsylvania. Benjamin was his grandson.From: Robert G. Ferris (editor), Signers of the Declaration: Historic Places Commemorating the Signing of the Declaration of Independence, published by the United States Department of the Interior, National Park Service: Washington, D.C. (revised edition 1975), pages 123-126:
The father of Benjamin Rush died when he was only six years old, and he and a brother were left entirely to the care of his mother. She was anxious to give Benjamin a classical education, but the earnings from her small farm did not supply her with adequate means. Intent upon her purpose, she sold her land and moved to Philadelphia, where she commenced some commercial pursuit. She was successful; and her wish to give her eldest son a liberal education, was gratified. At the age of nine years he was placed under the care of the Rev. Dr. Findlay, who was the principal of an academy at Nottingham, in Maryland...
Doctor Rush espoused the patriot cause immediately after his return to America, in 1768, and his pen proved a powerful instrument, in connection with his personal exertations, in arousing the people to action. He was solicited to take a seat in the General Congress of 1775, but declined; but when, in 1776, some of the Pennsylvania delegates in Congress refused to vote for Independence and withdrew from their seats, he was elected to fill one of them, and obeyed the call of duty by accepting it. He was not a member when the Declaration was adopted, but was present and signed it on the second of August following.
In 1777, Congress appointed Doctor Rush to the office of physician-general of the military hospitals of the middle department, in which he was of great utility. He did not serve again in Congress after that appointment; in fact, with the exception of being a member of the Convention of Pennsylvania, which adopted the Federal Constitution, he did not actively participate in any public duties. He was appointed president of the mint in 1788, which office he held fourteen years.
Although the services of Doctor Rush were eminently useful as a statesman, yet as a medical practitioner and writer, he was most distinguished and is most intimately known. He was appointed professor of chemistry in the Medical College of Philadelphia, in 1769, the year after his return from Europe. He was made a professor of the theory and practice of medicine in 1789; and at that time he also held the professorship of the Institutes of Medicine and of Chemical Science, in the Medical College of Pennsylvania. On the resignation of Doctor Kuhn, in 1796, he succeeded that gentleman in the professorship of the practice of medicine. These three professorships he held during his life.
Doctor Rush's eminent qualities as a medical practitioner, a philanthropist, and a Christian, were fully developed when the yellow fever rapidly depopulated Philadelphia, in 1793. It was so malignant, that all the usual remedies failed, and the best medical skill was completely foiled. Many physicians became alarmed for their own safety and fled from the city; but Doctor Rush, and a few of his attached pupils and friends, remained to aid the sick and dying, and, if possible, check the march of the destroyer. He at length had a severe attack of the fever and some of his pupils fell victims; but so long as he was able to get form his bed, he did not remit his labors.
When alarm seized upon many of the resident physicians of Philadelphia, and they fled from the danger, Doctor Rush called together some of his pupils and professional friends, and in an impressive manner laid before them their solemn responsibilities to their profession and to the public. He portrayed the effects upon the public mind which the flight of physicians would produce -- predisposing the system, through fear, to take the disease -- and he conjured them to remain. He concluded his earnest appeal, by saying: "As for myself, I am determined to remain. I may fall a victim to the epidemic, and so may you, gentlemen. But I prefer, since I am placed here by Divine Providence, to fall in performing my duty, if such must be the consequence of staying upon the ground, than to secure my life by fleeing from the post of duty allotted in the Providence of God. I will remain, if I remain alone." He and a few of his noble-hearted pupils remained and performed their duties faithfully. His written description of that dreadful epidemic, is one of the most thrilling pieces of composition in our language.
The impress of Dr. Rush's mind and energy is upon several public institutions. He formed the Philadelphia Dispensary in 1786, and he was one of the principal founders of Dickerson College, at Carlisle, Pennsylvania. In addition to honorary membership in many literary and scientific societies abroad, he held various offices in benevolent and philosophical institutions at home.
Among others, he was President of the American Society for the abolition of slavery; President of the Philadelphia Medical Society; Vice President of the Philadelphia Bible Society; one of the Vice Presidents of the American Philosophical Society, etc. etc.
As a patriot, Doctor Rush was firm and inflexible; as a professional man he was skillful, candid, and honorable; as a thinker and writer, he was profound; as a Christian, zealous and consistent; and in his domestic relations, he was the centre of a circle of love and true affection. Through life the Bible was a "lamp to his feet" -- his guide in all things appertaining to his duty toward God and man. Amid all his close and arduous pursuit of human knowledge, he never neglected to "search the Scriptures" for that knowledge which points to the soul aright in its journey to the Spirit Land. His belief in revealed religion, and in the Divine Inspiration of the Sacred Writers, is manifested in many of his scientific productions; and during that period, at the close of the last century, when the sentiments of infidel France were infused into the minds of men in high places here, Doctor Rush's principles stood firm, and his opinions never wavered.
The life of this truly great man terminated on the nineteenth day of April, 1813, when he was in the sixty-eighth year of his age. During his last illness, the public mind was greatly affected, and his house was constantly thronged with people inquiring concerning the probable result of the disease that was upon him. When death closed his eyes, every citizen felt that a dear friend had been taken away, and a general gloom overspread the community.
Doctor, medical educator, chemist, humanitarian, politician, author, reformer-moralist, soldier, temperence advocate, abolitionist--Benjamin Rush was all of these. One of the youngest signers [of the Declaration of Independence], only 30 years of age at the time, he was already a physician of note.
...While prospering as a physician, Rush cultivated the friendship of such men as Thomas Jefferson, John Adams, and Thomas Paine. In fact, Rush suggested to the latter that he write his famous tract Common Sense (1776), supplied the title, and aided in its publication.
...His work among the insane at the Pennsylvania Hospial resulted Medical Inquiries and Observations Upon the Diseases of the Mind (1812), which to some degree foreshadowed modern psychiatric techniques...
Aroused by the idealism of the Revolution as well as the plight of the poor and sick he encountered in his medical practice, Rush helped pioneer various humanitarian and social movements that were to restructure U.S. life in the 19th century. These included abolition of slavery and educational and prison reform. Rush also condemned public and capital punishment and advocated temperance. Many of his reform articles appeared in Essays: Literary, Moral, and Philosophical (1798).
Finally, Rush helped organize and sat as a trustee of Dickinson College (1783); aided in founding the Pennsylvania Society for Promoting the Abolition of Slavery (1787) and later served as its president; enjoyed membership in the American Philosophical Society; and was a cofounder and vice president of the Philadelphia Bible Society, which advocated the use of scripture in public schools.
A typhus epidemic claimed Rush's life at the age of 67 in 1813. Surviving him were six sons and three daughters of the 13 children he had fathered. His grave is in Christ Church Burial Ground at Philadelphia.