Little seems to be known about John Cowan's birth and early life but he is believed to have been born around the year 1778. It seems most probable that he studied theology under John M'Millan III., who was the instructor for the Reformed Presbytery in Scotland around the time of his presentation for the ministry. He appears in the records of the Reformed Presbytery first as a candidate for licensure. He was licensed at Douglas on 9th of March, 1803, and was eligible to receive calls. His competence may be seen in the fact that by 1804, he had received two calls--one to the congregation at Chirnside; the other to the congregation at Stranraer. At a meeting, on August 15, 1804, he chose the latter and was duly ordained there, November 21 of that year. From that time, his presence in the presbytery was regular and he was chosen moderator of the Reformed Presbytery in 1805/6. He remained the minister of Stranraer until his death which occurred on January 13, 1817. The Synod, in its notice of his death, recorded that "he had labored with great acceptance in his charge," and also that he been to the Synod " a most amicable and valuable member." His literary output was sparse but the specimens of his writings which survive display his theological acumen and pastoral demeanor.