Armstrong, James (1781?–1839), unitarian minister and educationist, was born at Ballynahinch, Co. Down, where his father John Armstrong (1754?–1837) was a merchant; his mother, Margaret (1751?–1836), was a daughter of John Strong (d. 1780), presbyterian minister at Ballynahinch (1744–80) and moderator of the Synod of Ulster (1772). John and Margaret Armstrong had two younger sons, John Strong (fl. 1820s) and William (1786–1816), and three daughters, the second of whom, Anne (d. 1857), married William Crozier (1796?–1873), presbyterian minister at Rademon, Co. Down. James Armstrong later claimed ‘forefathers, paternal and maternal’ who had been ‘strict presbyterians in Scotland and suffered persecution for their principles (some even unto death) in the reign of Charles the Second’ (Ordination service, app., p. 77). In his youth he attended the Rademon academy of Moses Neilson (1739?–1823), father of William Neilson (qv). Financial losses sustained by the Armstrong family in the 1798 rebellion obliged the young James to take employment as an assistant at the Belfast Academy of William Bruce (qv), where he lived for the next eight years. During this time, when aged 18, he matriculated at TCD (6 January 1800). Apparently he did not attend lectures or graduate BA; whether he sat examinations is unclear; twelve years after matriculating he graduated MA (1813). While a master at the Belfast Academy he determined to become a minister, attached himself to the presbytery of Antrim (which did not require subscription to the Westminster confession of faith), and spent some months in Edinburgh studying theology. By 1807 he was an MA (presumably of Edinburgh).
Having been licensed by his own presbytery (11 May 1806), he was ordained by the Dublin presbytery (also non-subscribing) for a Dublin congregation, that in Strand St. (25 December). At first he was assistant to John Moody (b. 1740?); at Moody's death (July 1813) he was chosen to succeed; he was sole minister until 1815 when William Hamilton Drummond (qv) was installed as joint minister of the congregation (25 December). Armstrong was the leading light in Dublin of the unitarianism that was affecting some of the old-established presbyterian congregations in Ireland (as in England). As clerk of the Synod of Munster (the non-subscribing body outside Ulster), he was influential. He was a founder of the Irish Unitarian Society (1830) and of the Association of Irish Non-subscribing Presbyterians (1835). He was awarded a Doctorat en Théologie by Geneva University (12 September 1834) and visited the Swiss city on the tercentenary of the reformation there (1835). Inevitably, his unitarianism brought him into dispute with trinitarian Presbyterians. Ironically, Armstrong befriended Henry Cooke (qv) when the latter was living in Dublin (1817–18); he recommended him for the succession to a non-subscribing minister at Killyleagh, Co. Down, where, not long after his appointment, Cooke appeared as a champion of trinitarian orthodoxy (1821) and a few years later as a public adversary of Armstrong (1825). Armstrong's main published theological contributions to the controversy were The sin against the Holy Ghost (1836), a sermon preached in London and issued as a pamphlet, and A sermon vindicating the principles of unitarian Christianity (1838), which provoked both support and criticism.
Armstrong is notable as the historian of presbyterianism in Dublin, having contributed an invaluable historical introduction and a prosopography as an appendix to Ordination service: sermon at the ordination of the Rev. James Martineau (1829). An accomplished scholar, with a good knowledge of Hebrew as well as Greek and Latin, and of Italian as well as French, and an amateur interest in botany, he was elected MRIA (27 January 1834). His earliest publication, Observations on the state of education in Belfast in a letter to James MacDonnell (1807), though written to protect the Belfast Academy from competition from a proposed new college, shows a deep knowledge of pedagogy; after settling in Dublin he conducted (until c. 1830?) a school preparing university entrants. He was a governor of the Charitable Infirmary, Jervis St. James Armstrong died 3 December 1839 at a wedding reception and was buried at Mount Jerome.
He married (26 September 1811) Mary Allman, daughter of a cotton merchant, George Allman, and his wife Maria (née Clugston), both of Bandon, Co. Cork; James and Maria Armstrong, who lived in Hardwicke St., Dublin, had, beside four daughters, two sons, both of whom graduated at TCD (1834), John (b. 1812), called to the bar (1837) and notable as an antiquary, and George Allman (1815?–89), admitted as a solicitor but later a minister and assistant to Drummond at Great Strand St. (from 1841).
James Armstrong is featured in a painting of an imaginary event, ‘Military procession in Belfast in honour of Lord Nelson’, by Thomas Robinson (qv), father of a promising pupil at the Belfast Academy, Thomas Romney Robinson (qv), in whom Armstrong took a particular interest; he is distinguishable near the extreme right of the canvas, wearing a hat and with his arm about the shoulders of the younger Robinson. Another portrait by the elder Robinson (c. 1809) shows Armstrong, head and shoulders, in clerical attire. The paintings are now held by the Belfast Harbour Commission and the Ulster Museum respectively. As a result of the dispute among Irish presbyterians over unitarianism, Maria Armstrong, having been widowed, was in danger of being left without financial support. A presbyterian trinitarian began proceedings in the court of chancery intended to deprive the unitarian congregations at Great Strand St. and Eustace St., Dublin, of their meeting-houses and funds. The judgment of the lord chancellor, Edward Sugden (qv), was in his favour, unitarians thereby being deprived of benefit from the so-called ‘general fund’ set up in 1710 for ‘protestant dissenters’. Armstrong, a trustee, had published an account of this fund, Short account of the general fund (1815). The matter was settled satisfactorily by the Nonconformists’ Chapels Act (19 July 1844).