The parish church of St John the Baptist, Aberdare, is an ancient building with Chancel nave and west turret containing one bell. It is believed to have been built in 1189 A.D and was originally a chapelry of the parish of Llantrisant. The building consists of a nave and square chancel to which a vestry was added much later in 1795. In 1637, a bell was presented by a local landowner, William Mathew of Aberaman, which is still in constant use. The parish registers date from 1735 and provide valuable information about births,marriages and deaths, as well as details of parish administration. Unfortunately, the Churchwardens' Account Books have not survived. In 1749, John Wesley visited the parish church. "I came to Aberdare just as the bell was ringing for a burial. This brought a great number of people together, to whom,after the burial, I preached in the church". By 1841, the fabric of the church was in a very bad state; the roof was in a state of collapse and the windows were broken. The dramatic increase in the population of Aberdare after 1840, due to the development of the iron and coal-mining industries,led to the building of new churches: St Elvan (1852), St Ffagan (1854), St Lleurwg(1858) And St Mair(1868). There were proposals to enlarge and even to demolish the parish church, but nothing of importance happened until the 1870's when it underwent "restoration ". The collection of wall tablets is of interest because of the light they cast on Noteworthy families. An unusual tablet to the left of the West door records the burialof David Watkins of Aberaman in 1789, who was buried perpendicularly at his own request. This has been interpreted to mean that he was buried " within the wall",although it could also have meant perpendicularly "below the wall". When the graveyard was laid out in walks in 1972, most of the gravestones were set against the West wall where they continue to show the frailty of life in the Parish in the nineteenth century.
Visitors to this much-loved church can glean further information from the handbook entitled "The church of St John the Baptist,a brief history", by Geoffrey Evan(1980), which recaptures the central role it has played in keeping alive the flame of Christianity in the parish of Aberdare since 1189.