Gregorian chant
Christians have sung songs without music since the earliest days of the Church. Before the mid-1990s, many people believed that the Jewish songs called the "Psalms," which are in both the Jewish and Christian Bible, were an important part of early Christian music and prayer. People who study the history of music and religion no longer believe this, because most early Christian songs were not from the Psalms, and Jews did not sing Psalms for many centuries after their most important holy place, the Second Temple, was destroyed in the year 70. However, some parts of Jewish music and prayer ended up later in Gregorian chant. The organized order of prayers called "canonical hours" come from Jewish tradition. The words "amen" and "alleluia" come from the Hebrew language.  The prayer "sanctus, sanctus, sanctus," which means "holy, holy, holy," comes from the Jewish prayer "kadosh, kadosh, kadosh."