The divine and poet Ralph Erskine was born on 15 March 1685 at Monilaws in Northumberland. He was the sixth son of the Rev. Henry Erskine (1624-1696) by his second wife Margaret Halcro. Henry Erskine had settled in Northumberland in 1684 after a period of imprisonment on the Bass Rock. Ralph Erskine entered Edinburgh University in November 1699 studying an Arts course until 1704. Strongly religious as a child and influenced in young adulthood by the religious conversion of his sister-in-law who had married his brother Ebenezer Erskine (1680-1754), he himself became converted. After University he became tutor to the family of Colonel John Erskine of Culross, and he also pursued theological studies. In 1709 he was licensed by the Dunfermline Presbytery and was ordained in 1711.

After a dispute with General Assembly of the Church of Scotland in 1732, Erskine along with six other ministers formed the Scottish Secession Church with Ebenezer Erskine as their first Moderator.

In the late-1730s correspondence was begun between Erskine and George Whitefield (1714-1770) the Anglican cleric and evangelist who had gone to North America. The correspondence led to Whitefield coming to Scotland and his first sermon in Scotland was delivered at Erskine's own church.

It wasn't too long before Erskine's Secession Church was torn in two - over the taking of the Civil Oath by Burgesses in Edinburgh, Glasgow and Perth. The argument was over what was meant in taking that Oath and over what it meant by promising to oppose Catholicism. Those who opposed the Oath withdrew in 1747 and constituted themselves as the General Associate Synod.

Ralph Erskine is responsible for the following works: Gospel sonnets published early in his ministry and reaching a 10th edition in 1762 and a 25th in 1797 long after his death; a paraphrase of the Song of Solomon (1738); a version of the Book of Lamentations (1750). Job's hymns was published posthumously in in 1753. His Practical works in two volumes were edited by John Newlands, his son-in-law in 1764-1766.

In the 1750s, Erskine developed heart disease and his last sermon was held in late-October 1752. Ralph Erskine died on 6 November 1752, and he was buried in Dunfermline on 9 November.