Judaism
Christianity was originally a sect of Second Temple Judaism, but the two religions diverged in the first century. The differences between Christianity and Judaism originally centered on whether Jesus was the Jewish Messiah but eventually became irreconcilable. Major differences between the two faiths include the nature of the Messiah, of atonement and sin, the status of God's commandments to Israel, and perhaps most significantly of the nature of God himself. Due to these differences, Judaism traditionally regards Christianity as Shituf or worship of the God of Israel which is not monotheistic. Christianity has traditionally regarded Judaism as obsolete with the invention of Christianity and Jews as a people replaced by the Church, though a Christian belief in dual-covenant theology emerged as a phenomenon following Christian reflection on how their theology influenced the Nazi Holocaust.
Religious denomination
The movements differ in their views on various issues. These issues include the level of observance, the methodology for interpreting and understanding Jewish law, biblical authorship, textual criticism, and the nature or role of the messiah (or messianic age). Across these movements there are marked differences in liturgy, especially in the language in which services are conducted, with the more traditional movements emphasizing Hebrew. The sharpest theological division occurs between Orthodox and non-Orthodox Jews who adhere to other denominations, such that the non-Orthodox movements are sometimes referred to collectively as the "liberal denominations" or "progressive streams."