St. Valentine's Church dates mainly from the late 15th and early 16th centuries, with the side aisles of the church dating back to 1380. The construction of the church building was financed by donations from pilgrims who made a pilgrimage to the relics of St. Valentine. These relics arrived in Kiedrich around 1350 from the neighbouring Cistercian abbey in Eberbach. The church organ is one of the oldest still playable organs in the world, probably built from 1491 onwards. However, over the centuries the instrument has been transformed several times, most notably in 1653 by Johann Wendelin Kirchner.
The New Mainz Synagogue, inaugurated in 2010, is the successor building to the former Mainz Synagogues. Mainz, or Magenza as it is called by the local Jewish community, had been an important Jewish centre on the Rhine since Roman times, and lost its importance only with the Second World War. After the fall of the Berlin Wall, the high number of immigrants from Eastern Europe expanded the congregation in the 1990s and, as new premises had to be found, the construction of the synagogue was decided in 1999. Architect Manuel Herz received the German Façade Award for the Ventilated Curtain Wall (VHF) 2011 for the building.
The Christ Church in Mainz is a Protestant church built between 1896 and 1903 according to the plans of Eduard Kreyssig. The building is reminiscent of the Italian High Renaissance style. In addition to religious services, the Christ Church is also popular for music. Since 1954, the Mainz Bach Choir and Orchestra have been using the church regularly.