Grainau was originally subject to the mother church in Garmisch. Church ceremonies such as baptisms, weddings or funerals were held in Garmisch, and the people of Grainau also had to go to church services in Garmisch. Nevertheless, the villages had their own chapels. The chapel of Obergrainau on the Kirchbichl was built in 1697, around 1730 the chapel of Untergrainau and in 1783 the Hammersbacher Marienkapelle made of stones from the "Hammersbacher Burg".
In 1812 the first local priest moved into Grainau, in 1835 the mountain cemetery, which is well worth seeing, was built, and in 1927 the Obergrainau church was given its present appearance. The final ecclesiastical separation from Garmisch took place in 1945 with the establishment of the parish of Grainau.
The villages suffered little from the effects of war during the Freising period. Obergrainau, however, was not spared from fire and water. On March 12, 1779, a large fire destroyed 14 houses and the church. The narrow construction, the buildings made of wood as well as a great drought were the reason that at that time almost all properties around the upper village square fell victim to the fire. Only a few years later, on June 21, 1788, the Alplebach river flooded the village square and made two houses uninhabitable.