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.
Orthodox Judaism
Orthodox Judaism may be categorized according to varying criteria. The most recognizable sub-group are the "Haredim" (literally, "anxious" or "fervent"), also known as Ultra-Orthodox, strictly Orthodox and the like. They form the conservative, strict and self-segregating part of the Orthodox spectrum. "Haredim" are characterized by a minimal engagement with modern society and culture if not their wholesale rejection, by avowed precedence given to religious values, and by a high degree of rabbinic authority and involvement in daily life. In spite of many differences, "Haredi" rabbis and communities generally recognize each other as such, and therefore accord respect and legitimacy between them. They also hold a lukewarm or negative assessment of more modernist Orthodox groups. "Haredim" are easily discerned by their mode of dress, often all black for men and modest by religious standards for women (including hair covering, long skirts, etc.)