There is some doubt about the date of the first church on the site because authoritative records from the pre-Reformation period either have not survived or are inconclusive. Rev. James O’Laverty, believed that the Pope Nicholas Taxation of 1306 provides evidence for the existence of a church at Lambeg. The churches listed in that taxation do not include the name Lambeg but it does appear in a ‘terrier’, a list of lands belonging to the Bishop, of approximately the same period. The churches in the area are listed in the same order in both documents but the name Cloncolmoc in the taxation is replaced by Lambeg in the terrier. O’Laverty therefore believed that Cloncolmoc, ‘the meadow of St. Colman’, was the original name for Lambeg although Reeves disagreed believing that the site of Clomcolmoc was in the neighbouring parish of Drumbeg.
Two nineteenth-century sources, Lewis’ Topographical Dictionary of Ireland (1837) and the Ordnance Survey Memoirs of Ireland (1837), refer to a tradition in Lambeg that it was also the pre-Reformation site of a Franciscan monastery and a nunnery. A State Paper of 1601 and Archdall’s ‘Monasticon Hibernicum’ (1786) provide some evidence to support that tradition.
The earliest date for which there is definite proof of a church on the site is at the end of the 16th century. A church at Lambeg is clearly marked on a 1598 map of Ulster which is now held in the British Museum. However by 1657 ‘Lambeg: a small chapell or parish church’ was ruinous according to an Inquisition of that year. The parish was united in the same year with the parish of Blaris, i.e. Lisburn, until 1737 when a new chapel, built on the site of the 1657 ruin, was consecrated. That building was enlarged in 1824 and entirely rebuilt in 1849 with the tower now the only remaining part of the 1737 building.