Unionskirche, Idstein

The Unionskirche is the active Protestant parish church of Idstein, a town in the Rheingau-Taunus district in the German state of Hesse. Idstein was a residence of the counts of Nassau. The church building in the center of the historic Altstadt dates back to the 14th century when it was built as a collegiate church. It became Lutheran during the Reformation. Its interior was adapted in the 17th century to become a Lutheran "Predigt- und Hofkirche". The most prominent decoration in the church is the series of 38 paintings by the Flemish painter Michael Angelo Immenraedt, an exponent of Flemish Baroque painting, and others. They follow a program of Biblical scenes.

The church was named Unionskirche in 1917 to commemorate the union of Lutheran and Reformed Protestants in the Duchy of Nassau in August 1817, the first of its kind. The Unionskirche is a recognized monument under the Hague Convention.