The Viennese architect Otto Schöntal was a student of Otto Wagner at the Academy of Fine Arts and exhibited this project for a Schloßkapelle in the periodical Moderne Bauformen in 1908.
It combines a simplicity of form with greater complexity in its decoration but like the work of many of the more mid-ranking architects of the Secession it comes across as a bit rigid and angular despite a certain freeness in its design.
Love it. Puts me in mind of the Church of the Holy Spirit, Javorca, Slovinia, designed by Remigius Geyling and built by Austro-Hungarian troops as memorial to those who had died on the Italian front following the Battle of Isonzo. Here’s a link to the not entirely satisfactory website: https://www.javorca.info/en/