It is often debated whether Judaism is a race, religion, nation or ethnic group, and whether you can ever stop being a Jew. If you are born Jewish and then practice a different religion are you still Jewish? If you are born into a different religion and then convert to Judaism, are you ever a real Jew?

To decide whether Judaism is a race, religion, ethnic group or nation we need to clearly define these terms.

The first and most obvious is: 

RELIGION

Religion is a set of beliefs and practices concerning the meaning and nature of life, from which a set of morals, ethics or guidelines to living a better life are surmised. A religious group often shares a history, traditions, texts and symbols which define mans relationship with his fellow man, his inner self and in most cases a higher power or God.

Using this definition of religion Judaism is most definitely a religion.

Judaism has a holy text, religious symbols and traditions as well as a clearly defined set of beliefs, practices and moral values.

ETHNIC GROUP

Ethnic groups consist of people with a common heritage, history and cultural identity. An ethnic group can but doesn't have to include a common language, religion or culture. The group is distinctively different from other groups and marriage within the ethnic group is common and encouraged. Ethnic groups are a group of people united by elements beyond their control as they were born into the ethnic group although it is possible to join an ethnic group integration is not simple as one would have to assume a new cultural identity. You could say ethnic groups are a nation without a country.

Using this definition Jews are part of an ethnic group, you may find Ethiopian Jews, American Jews, Yemeni Jews, Russian Jews and although they don't share skin color, language or country they do share a common history and culture.

RACE

Race is a difficult word to define as it involves the grouping of people according to certain traits, the problem being which traits should be used for this classification. The word is used today too loosely.

Here is a dictionary definition:

a : a family, tribe, people, or nation belonging to the same stock b : a class or kind of people unified by shared interests, habits, or characteristics

http://www.merriam-webster.com/dictionary/race?show=2&t=1294152561

Another definition of race:

Any of the traditional divisions of humankind, the commonest being the Caucasian, Mongoloid, and Negro, characterized by supposedly distinctive and universal physical characteristics: no longer in technical use.

b.An arbitrary classification of modern humans, sometimes, esp. formerly, based on any or a combination of various physical characteristics, as skin color, facial form, or eye shape, and now frequently based on such genetic markers as blood groups.

c.A human population partially isolated reproductively from other populations, whose members share a greater degree of physical and genetic similarity with one another than with other humans"

http://dictionary.reference.com/browse/race

In light of these definitions it is debatable whether Jews are a race as they meet some of the criteria for a race and not others. Officially according to US law the Jewish race exists, this classification was created in order to include Jews in anti-discrimination laws. The Jews themselves often refer to themselves as a race, in the Bible they are referred to as a nation and a race. Also a race cannot be joined and you can convert to Judaism thus becoming a Jew but not a member of a new race!

Jewish people believe they are descendants ofAbraham, Isaac and Jacob all with a common blood line this may better be described as a family or a people.

However you define the Jewish people they are a distinct group of people sharing a bond which has stood the test of time.

 Sources:

http://www.merriam-webster.com/

 http://dictionary.reference.com/

http://www.jewfaq.org/judaism.htm

http://en.wikipedia.org/wiki/Ethnic_group

http://dictionary.reference.com/browse/race