Ecumenical comes from the Greek "oikoumene", which means "the whole inhabited world" and refers to an Ecclesial Movement aiming to unify all the Christians in the world.
The Patent of Tolerance by Joseph II, Holy Roman Emperor made it possible for local Lutherans to build a church located in Alsóbük (Lower-Bük).
The first mass was celebrated on the First Sunday of Advent in 1785 in the church which was built in a modest style and whose tower with a sheet metal spire was erected in 1826. According to the Patent of Tolerance, no church was allowed to be built in the main street or on the street side or with a tower.
The ground-plan is rectangular, the gallery is supported by wooden columns and the ceiling is made of wooden beams. The Greek Revival style altar and the pulpit behind with a urn crowning it is a work of art by a joiner with the monogram MM from 1795. The altar-piece of the church was made in 1884. The baptismal font is original, supported by baluster legs.
Until the 1880s, the church walls were decorated by coats of arms of noble Lutheran families from Bük. Nowadays, there is marble plate commemorating bishop Gyurátz Ferenc (1841–1925), born in a family in Alsóbük.