Pirie was for some time a minister connected to the Antiburgher Synod of the Presbyterian Church of Scotland.
In 1760, he was appointed a teacher of the Philosophical Class in the Theological Seminary in New York City, but was suspended and expelled shortly after.
On joining the Burghers, he returned to Scotland and became minister of a congregation in Abernethy. In 1769, he joined the Independents, and was pastored a congregation at Newburgh, Fifeshire. His works include: