The next minister was Rev Dr. Henry Montgomery (afterwards LL.D.), who was ordained on 14th September 1809 at the age of 21. Rev Dr. Montgomery was the great leader of the Non Subscribers; and in 1829 he and the entire congregation seceded from the Synod of Ulster, to form the Remonstrant Synod of Ulster. He retained possession of the church, manse and other properties. A few years after this secession, and because of it, the congregation of Malone, in the neighbourhood of Dunmurry was erected by the Synod of Ulster; and on 15th February 1837 Mr. Joseph McKenzie was ordained as its pastor.
Dr. Montgomery was a brilliant orator and tireless worker for the rights of individuals, supporting Catholic emancipation, tenant right, education, poor laws, and many other causes. He died in 1865 and there is a marble memorial to his memory in the church on the wall to the right of the pulpit. Another commemorates his son who served with the Army in India and died on his way home from there.
On 18th December 2015, Very Rev William McMillan unveiled a Ulster History Circle Blue Plaque commemorating the Rev Henry Montgomery (1788-1865) on the walls of his old meeting house. View footage from this event below: