Origins of Judaism
For centuries, the traditional understanding has been that Judaism came before Christianity and that Christianity separated from Judaism some time after the destruction of the Second Temple in 70 CE. Starting in the latter half of the 20th century, some scholars have begun to argue that the historical picture is quite a bit more complicated than that. In the 1st century, many Jewish sects existed in competition with each other, see Second Temple Judaism. The sects which eventually became Rabbinic Judaism and Early Christianity were but two of these. Some scholars have begun to propose a model which envisions a twin birth of Christianity and Judaism rather than a separation of the former from the latter. For example, Robert Goldenberg (2002) asserts that it is increasingly accepted among scholars that "at the end of the 1st century CE there were not yet two separate religions called "Judaism" and "Christianity"".
Daniel Boyarin (2002) proposes a revised understanding of the interactions between nascent Christianity and nascent Rabbinical Judaism in Late Antiquity which views the two religions as intensely and complexly intertwined throughout this period.
Hashkafa
With the rise of Jewish philosophy and great Jewish thinkers, various sects of Orthodox Judaism have developed throughout history, each with their distinct hashkafa. While certain meta-principles are present in all sects—primarily the ones precisely demarcated in the Torah and Talmud, others have been the subject of much disagreement, especially those that deal with pertinent and pressing issues. Despite the vast differences between Hasidism and Modern Orthodoxy, both are still considered legitimate. The idea that there can be more than one correct understanding is deeply rooted in Jewish texts. The most well known of such statements is from the Midrash—the collection of exegesis of Torah taught by Rabbinical Sages of the post-temple era—in Bamidbar Rabbah 13:15, which explains that there are "seventy faces to Torah". This perplexing statement is generally understood to mean that the nature of the Torah's truth is multifaceted. Similarly, the Babylonian Talmud states regarding a legal debate that "these and these are the words of the living Lord"; in other words, both opinions are valid. Because no single hashkafa is believed to have a monopoly on the truth, great amount of philosophical flexibility is provided to Jewish thinkers, which results in different—sometimes even contradictory—hashkafas.