In the 19th century, the parish of Blanchardstown in the Catholic Church encompassed much of the area now within the Dublin 15 postal district. Following the relaxation of the Penal Laws, it became possible for Catholics to consider the construction of additional churches and to repair the existing stock of religious buildings. St Brigid's Church Blanchardstown, not to be confused with a church of the Church of Ireland in nearby Castleknock, was constructed in 1837 upon the foundation of a church that had been built prior to 1731. It is the Mother church of 12 other churches constituted out of the parish over the following 156 years. Among these was the church of the Nativity of the Blessed Virgin Mary. The parish separated from Blanchardstown 1883. The eastern part of the new parish was in turn constituted out of Chapelizod in 1953 as the Navan Road parish of Our Lady Help of Christians.