 He graduated with a Master of Arts degree in 1585 from the University of St Andrews, becoming minister of Fettercairn in the Mearns in 1588, using this position to take an active role in the church politics of the day.As a result, on 22 November 1604, he became Bishop of Caithness, retaining control of Fettercairn, something which created animosity with the anti-episcopal section of the Church of Scotland.Forbes took part in most national church meetings in this period, and was part of the meeting at Glasgow in 1610 which restored the old authority and powers of bishops.