“It should have been remarked ere now, that during all his ministry McCheyne was careful to use not only the direct means appointed for the conversion of souls, but those also that appear more indirect, such as the key of discipline…
Once from the pulpit, at an ordination of elders, he gave the following testimony upon this head:
‘When I first entered upon the work of the ministry among you, I was exceedingly ignorant of the vast importance of church discipline. I thought that my great and almost only work was to pray and preach.
I saw your souls to be so precious, and the time so short, that I devoted all my time, and care, and strength, to labour in word and doctrine. When cases of discipline were brought before me and the elders, I regarded them with something like abhorrence.
It was a duty I shrank from; and I may truly say it nearly drove me from the work of the ministry among you altogether.
But it pleased God, who teaches His servants in another way than man teaches, to bless some of the cases of discipline to the manifest and undeniable conversion of the souls of those under our care; and from that hour a new light broke in upon my mind, and I saw that if preaching be an ordinance of Christ, so is church discipline.
I now feel very deeply persuaded that both are of God,—that two keys are committed to us by Christ: the one the key of doctrine, by means of which we unlock the treasures of the Bible; the other the key of discipline, by which we open or shut the way to the sealing ordinances of the faith.
Both are Christ’s gift, and neither is to be resigned without sin.'”
–Robert Murray McCheyne and Andrew A. Bonar, Memoir and Remains of the Rev. Robert Murray McCheyne (Edinburgh; London: Oliphant Anderson & Ferrier, 1894), 79–81.