On June 20, 1859 five men: H.Landsmann, W.Trampe, M.Koehler, H.Klages, and W. Lange met to form what was called "The First German Evangelical Lutheran Church of Carondelet". In 1872, when the current church was built, the name officially changed to "The Evangelical Lutheran St. Trinity Congregation U.A.C.". The name "St. Trinity" was the result of an error in translation of the Articles of Incorporation from German into English by Charles Frincke, Jr. The actual German name was "Heilige Dreieinigkeit", meaning Holy Trinity, or from the Latin, "Sanctus Trnitatus". The church building of 1872, designed by Rev. Stephan is still the current sanctuary used today. The cornerstone for the building was laid on September 27, 1872 and was dedicated June 29, 1873. The present Kilgen organ was installed in 1903.
Early in 1860, Otto Hanser was called to be the first pastor of the new congregation. Later that same year, George Steuber was called to be the first teacher for the school that was formed when the church first began.
Pastor Hanser served until the fall of 1862 when he took a call to Boston and the congregation called Rev. Hamann. He served until 1868 when poor health prompted him to ask for a leave of absence and the congregation called C.F.W. Sapper with the promise that he would become the pastor if Rev. Hamann could not continue his duties. Shortly thereafter, Rev. Hamann retired and Rev. Sapper served the congregation faithfully for the next 17 years.