He was licensed by the Armagh presbytery, declined in 1776 a call to Keady, co. Armagh, and in the following year, on the death of Alexander Colville, M.D., the non-subscribing minister of Dromore, co. Down, he accepted the call of this congregation, which returned to the jurisdiction of the general synod of Ulster.
On 15 February 1782 he attended the convention of Irish volunteers at Dungannon as captain, Robert Black, and seconded the resolution adopted in favour of catholic emancipation.
As agent for the royal bounty, he exerted himself to secure its augmentation; in 1792, by help of the Earl of Charlemont, Henry Grattan, and Colonel Stewart of Killymoon, the Irish parliament passed a favourable resolution, and 500l.
The seditious tendencies now beginning to appear in the volunteer movement excited his alarm, and he delivered a solemn warning against them in a speech at a meeting of the parishioners of Templemore held in Derry Cathedral on 14 Jan. 1793 (see abstract in Belfast News-Letter, 25 Jan. 1793).
In the rebellion of 1798 he was strongly on the side of constituted authority, and had great influence as the friend and correspondent of Castlereagh.
In theology he was strongly suspected of heresy, a view which is countenanced by the fact that in 1804 he endeavoured to secure as his colleague William Porter, whose Arianism was openly known.
His local prestige was impaired by the circumstances of Castlereagh's defeat at the county Down election of 1805, but his influence at Dublin Castle was equally strong with all ministries.
In 1809 the synod publicly thanked him for his exertions in procuring the act of parliament incorporating the widows’ fund.
In 1813 his controversy with William Steele Dickson, D.D., one of the chief victims of the rebellion of 1798, was ended by a synodical resolution declaring that words in a previous resolution (1799), complained of by Dickson, had been ‘inaccurately used;’ but Black's influence was still powerful enough to cause the expulsion of an elder who, in the course of debate, had laid charges against him in connection with the bounty.
There is a curious caricature engraving of Black in ‘The Patriotic Miscellany’ 1805, a collection of squibs relating to the Down election of that year.