His father's old congregation at Strand Street, Dublin, then called him on 24 March 1782 as colleague to John Moody, D.D., on the death of Thomas Plunket.
In the troubles of 1797 and 1798 he enrolled himself as a private in the Belfast Merchants' Infantry, sent his family to Whitehaven, and continued to preach; many of the more liberal Presbyterians had been in favour of the Irish Rebellion of 1798.
[2] At this period Bruce founded (23 October 1801) the Belfast Literary Society, and his advice was sought by the orthodox leaders of the General Synod of Ulster.
In the preface (dated 17 March) to his Sermons on the Study of the Bible (1824) Bruce claimed that his Unitarian views were "making extensive though silent progress through the general synod of Ulster".
[2] By 1834 Bruce had retired, and was suffering from a loss of sight, which ended in blindness in November 1836 he moved to Dublin with his daughter Maria, where he died on 27 February 1841.
His view of the freedom consistent with Presbyterian discipline was written up in the supplement "by a member of the presbytery of Antrim" to the Newry edition (1816) of Micaiah Towgood's Dissenting Gentleman's Letters.
[2] Besides these works, Bruce contributed papers to the Transactions of the Royal Irish Academy, Belfast Literary Society, Dublin University Magazine and other periodicals.
A series of twenty-three historical papers on the "Progress of Nonsubscription to Creeds" went to the Christian Moderator, 1826–8, with extracts from original documents.
His "Memoir of James VI", in Transactions of the Royal Irish Academy, 1828, published original letters, and information on his ancestor Robert Bruce of Kinnaird.