Bethune studied at Marischal College, Aberdeen from 1738 to 1742. He then studied Divinity first at St Andrews University then at Edinburgh University. As was then normal for ministers, whilst awaiting a post, he was private tutor to the children of the Carruthers of Holmains in Dumfriesshire. He was licensed to preach by the Presbytery of the Church of Scotland in Lochmaben in March 1750. He was eventually ordained at Rosskeen in October 1754.
