William Bentley was born on June 22, 1759, in Boston, the son of Joshua Bentley and Elizabeth Paine. Bentley's grandfather, William Paine, was the benefactor of his education at Harvard College which he entered in 1773 at the age of fourteen. After graduating with high honors in 1777, Bentley taught at Boston grammar schools for three years, until he was appointed a tutor in Latin and Greek at Harvard. During this time, he developed a growing reputation as a popular speaker in Boston.

On September 24, 1783, Bentley was ordained as the pastor of the East Church in Salem, Massachusetts. He served as a co-pastor for two years before becoming the sole pastor of East Church in 1785, a position he held until his death.

Rev. Bentley was an accomplished scholar who had a reading knowledge of more than twenty different languages, including a familiarity with Arabic and Persian. He also wrote and spoke most of the popular European languages. Rev. Bentley also had many varied interests including, but not limited to, natural history, coins, and rare books. His days were filled with writing sermons for the forthcoming Sabbath, writing to his many correspondents both in the United States and abroad, reading books in both English and foreign languages, and recording detailed information in his diaries of the births, baptisms, marriages, illnesses, and deaths that had occurred in the parish, and the arrival and departure of all sailing vessels owned by parishioners. Rev. Bentley also contributed to the town newspapers, The Gazette and The Republic by writing two columns twice a week for close to thirty years.

During the administration of President Thomas Jefferson, he was a candidate for the chaplaincy in Congress, a position he declined. Later, when Jefferson was planning the construction of the University of Virginia, he not only consulted with Bentley, he also extended Bentley the honor of becoming the University's first president but Bentley declined this position too, citing "he had been so long wedded to the East Church, he could not think of asking a divorce from it." Rev. Bentley died unexpectedly from angina pectoris in the Crowninshield home on December 29, 1819.