After three years spent in a charge at Worcester, he returned as head of Daventry Academy, a post which he continued to hold till 1789, when, having adopted Unitarian principles, he resigned.
In 1805, he accepted a call to the Essex Street Chapel,[1] which was also headquarters and offices of the Unitarian Church under John Disney, there succeeding as minister Theophilus Lindsey who had retired and died three years later in 1808.
(1806)[4] Belsham's first work of importance, Review of Mr Wilberforces Treatise entitled Practical View (1798), was written after his conversion to Unitarianism.
[5] Belsham was one of the most vigorous and able writers of his church, and the Quarterly Review and Gentlemans Magazine of the early years of the 19th century abound in evidences that his abilities were recognized by his opponents.
[6] [Thomas Belsham et al.,] The New Testament, An improved version upon the basis of Archbishop Newcome's new translation with a corrected text and notes critical and explanatory.