Orthodox Judaism is characterized by belief that the Torah and its laws are Divine, were transmitted by God to Moses, are eternal, and are unalterable; belief that there is also an oral law in Judaism, which contains the authoritative interpretation of the written Torah’s legal sections, and is also Divine by virtue of having been transmitted in some form by God to Moses along with the Written Law, as embodied in the Talmud, Midrash, and innumerable related texts, all intrinsically and inherently entwined with the written law of the Torah; belief that God has made an exclusive, unbreakable covenant with the Children of Israel to be governed by the Torah; adherence to Halakha, or Jewish law, including acceptance of codes, mainly the Shulchan Aruch, as authoritative practical guidance in application of both the written and oral laws, as well as acceptance of halakha-following Rabbis as authoritative interpreters and judges of Jewish law; belief in Jewish eschatology. Orthodox beliefs may be most found in their adherence to the thirteen Jewish principles of faith as stated by the Rambam (Maimonides).
Although Orthodox Jews are expected to observe all 613 mitzvot, certain core practices are generally considered essential to being Orthodox and converts are generally required to promise to observe:
• Refraining from murder, idolatry, and certain biblically-prohibited sexual practices such as adultery and incest (See Self-sacrifice under Jewish law).
• Shabbat, refraining from activities that violate the Jewish sabbath, and Jewish holidays.
• Kashrut, the Jewish dietary laws.
• Taharat Hamishpacha, the laws of family purity, restricting sexual relations around menstruation and childbirth.
• Circumcision for males.
The fact that Orthodox Judaism is, in the words of historian Jonathan Sarna, the “great success story of late 20th-century American Judaism” may seem surprising; a religion that believes in strict adherence to rules and rituals thrives at a time when personal choice seems to reign as the cultural norm. But traditional religious values can be said to be the great success story of many major religious groups since the 1970s; witness the phenomenal rise of evangelical Christianity and Mormonism as examples. In Judaism, the Reform movement, long so averse to tradition that the wearing of yarmulkes was officially barred from some synagogues, has itself embraced a more traditional path of observance.
The shift to the right is a product of many factors. Traditional religious groups tend to be more aggressive — and successful — in proselytizing for new members. While Orthodox Judaism rejects proselytizing non-Jews, it does embrace kiruv, the concept of working to convince non-observant Jews to adopt a more traditional lifestyle. Through organizations like the National Council of Synagogue Youth (NCSY), Chabad Lubavitch, Aish HaTorah, and others, many non-Orthodox Jews have been brought into the Orthodox fold in recent decades.
In addition, the rise of conservative religion is likely a reaction against the increased permissiveness and anything-goes attitude of secular culture. Boundaries and rules attracted many people today just as the removal of such behavioral limits attrracted the youth of the ’60s and ’70s.
Orthodoxy also has higher birthrates than other Jewish communities; sends a much-higher percentage of its children to Jewish day schools; has a much lower intermarriage rate (and children of intermarriages have a higher likelihood of being uninvolved in Jewish life); and generally have a much higher rate of participation in Jewish life — all factors that help to strengthen Orthodox communities and make it attractive for non-Orthodox Jews to join.
And the Orthodox Jewish lifestyle is easier than ever before. The affluence most Jews have achieved — together with changing societal norms — makes working on Shabbat less of a necessity. The plethora of kosher food in supermarkets worldwide eases observance of the dietary laws, and the growth of kosher restaurants in many cities reduces the inclination among many Orthodox Jews to eat in non-kosher establishments. Religious book and CD publishing is thriving and an industry of Jewish-items producers seems to make observance ever-simpler, with innovations such as a snap-together sukkah, Shabbat-friendly kitchen appliances, and Passover-kosher food from pizza to granola bars to hamburger buns.

Rambam’s 13 Principles of Faith are an excellent summary of the core beliefs of Orthodox Judaism.
• I believe with perfect faith that God is One. There is no unity that is in any way like His. He alone is our God. He was, He is, and He will be.
• I believe with perfect faith that God does not have a body. Physical concepts do not apply to Him. There is nothing whatsoever that resembles Him at all.
• I believe with perfect faith that God is first and last.
• I believe with perfect faith that it is only proper to pray to God. One may not pray to anyone or anything else.
• I believe with perfect faith that all the words of the prophets are true.
• I believe with perfect faith that the prophecy of Moses is absolutely true. He was the chief of all prophets, both before and after Him.
• I believe with perfect faith that the entire Torah that we now have is that which was given to Moses.
• I believe with perfect faith that this Torah will not be changed, and that there will never be another given by God.
• I believe with perfect faith that God knows all of man’s deeds and thoughts. It is thus written (Psalm 33:15), “He has molded every heart together, He understands what each one does.”
• I believe with perfect faith that God rewards those who keep His commandments, and punishes those who transgress Him.
• I believe with perfect faith in the coming of the Messiah. How long it takes, I will await His coming every day. 13. I believe with perfect faith that the dead will be brought back to life when God wills it to happen.