From yahoo answers...
Best Answer: When asked to sum up the Torah in one sentence, one of Judaism greatest sages stated:
That which is hateful to you, do not do to others. The rest is commentary, now go study the commentary.
As for your other questions:
1. Judaism is a strictly monotheistic religion with one god. In daily conversation, most Jews refer to Him using the Hebrew 'HaShem' (The Name) or English 'G-d'.
2. Judaism does not have official dogma regarding what happens to us when we die, therefore, no heaven or hell. There are some loose theories of what might happen though:
* When we die, our souls are cleansed of any wrongdoings. This is done by our accounting of every action done in life. It's believed that this process takes no longer than 12 months but most people don't do enough bad in life to warrant it taking a full 12 months.
* Our souls return to HaShem to wait for the world to come.
* Our souls may be reincarnated into different people so that we have additional chances to work to become closer to HaShem.
* Those souls that choose to be truly evil in life, cannot survive the process of cleansing and cease to exist.
3. Just like there are Jews who are good people and Jews who are bad people, the same goes for all other people regardless of religion or lack thereof. Judaism is pluralistic in that it teaches that there are different paths for different people. So long as an individual's beliefs help them to be a good person, all is good.
To correct other posters' grossly incorrect claims about Jews and Judaism:
1. The names 'Yahweh' and 'Jehovah', and any variation, are Christian in origin and have NEVER been used by Jews at any time in history.
2. The Jewish Bible is called the 'Tanach'. Although the Christian Old Testament was based on the Tanach, the OT was completely altered to support the teachings of Christianity. The Christian OT is not seen as a valid religious text for Jews.
3. There is no "main prophet" in Judaism. Judaism has thousands of prophets and Moshe (Moses) is considered the greatest, but he is not the "main prophet".
4. The Talmud is not a holy book and it was not written by prophets. It is a vast collection of recorded discussions of scholars, debates, religious decisions, legend, and other scholarly topics.
5. Not only is salvation not a main theme in Judaism, the Christian concept of salvation simply does not exist in Judaism.
6. Judaism has three forefathers, not just one: Avraham, Yizchak, Ya'akov.
7. There is no such thing as a Jewish race, Jews come in all colours.
8. Jews do not seek converts. See point 3 from the first part.
9. Judaism and Christianity hold virtually nothing in common. This is mainly because Christianity was based on a rejection of Judaism. The core tenets of Christianity diametrically oppose those of Judaism.
10. Jews do NOT consider Jesus to be a prophet. In truth, Jesus barely enters the thoughts of most Jews unless a Christian mentions him to us.