Irmenach belonged to the “Hinder” County of Sponheim and thus shared its history. In particular, its proximity to the Grevenburg (castle) often led to occupation by enemy armies, under which the villagers suffered greatly. In 1557, the Reformation was introduced into Irmenach, as it was throughout the County. Ever since, Irmenach has been an Evangelical (Lutheran) community. Nevertheless, there might have been a few families who were under Electoral-Trier serfdom and who therefore remained Catholic, even if – unlike what happened in other municipalities – a simultaneum was never instituted at the church. Only in recent times has the Catholic share of the population grown somewhat with newcomers.