Judaism is based on the Bris(Brit/Brith: A covenant or agreement) Hashem made with the Nation of Israel under the leadership of Moshe at Mt. Sinai. The Torah is the record of our obligation to Hashem, fulfilling our side of the Bris.
A Jew by definition is a member of the Bris. Although the usual way of becoming Jewish is by being born to a Jewish mother this is not the only means. Any individual regardless of status at birth has the option of becoming a Jew through Geirus (Conversion).
The fact that one can become a Jew shows that, despite we believe Jews have a special role and relationship with Hashem, Judaism is certainly not racist since any individual regardless of race may become a Jew. Although Jews are "Chosen" a non-Jew may choose to be chosen as well. I remember attending a Shul in a Chareidi community in Israel, and Jews of all complexions attended together to serve Hashem.
A Jewish convert, one who is born to a non-Jewish mother but becomes Jewish is known as a "Geir" (or Geyr, Ger). A Geir has the same obligations as other Jews and will bear these responsibilities the rest of his life. It is not a decision to make quickly or on a whim. A Torah life is very demanding and it is far better for one to remain not Jewish than to accept the additional obligation of Torah's mitzvos upon one's self only to fail to live up to one's promise. For this reason conversion is discouraged in Judaism, it being in many ways preferable to remain a non Jew who observes the seven mitzvos given to Noach and all non Jews.
Jewish law gives us the requirement and procedure for Geirus. Now a Bris can be thought of like a contract between Israel and G-d and a convert is joining in on this contract. Conversion therefor is a legal procedure under Jewish law it must be done in the presence of a Beis Din: a court of Jewish law. The Beis Din determines whether the individual has the proper motives Jewish law requires of a Geir and makes sure the process is done according to halachah. Without a Beis Din there is no Geirus.
In order to become a Geir, one must accept the yoke of Torah. One cannot join the Bris without accepting the obligations of the Bris, just as it is useless to make a contract with someone who you know will not fulfill his side of the bargin. One must accept this yoke knowing that he is not required to, since a non-Jew need only observe the 7 Noachide Mitzvos and may have a share in the world to come. One cannot become a Geir in order to profit financially or to marry a Jew. One's reason's must be for the sake of Hashem.An individual will not be converted if their location, marriage, or other factors will prevent them from keeping mitzvos.
A male must undergo Bris Milah, ritual circumcision by a Mohel. Even if he was circumcised as a child he must nevertheless go through hatafas dam bris: a ritual circumcision done by drawing a drop of blood from the penis. Practically speaking, if the adult male is uncircumcised he may need to first receive a medical circumcision since the Mohel may not do adult circumcisions. Then, the Mohel will do the hatafas dam bris. The hatafas dam bris ceremony was painless. If anyone is considering conversion but needs full circumcision e-mail me and I will tell you my experience. For the record there is absolutely no requirement for female circumcision and it would be a violation of Jewish law and is completely foriegn to Torah.
All Geirim must go to the mikvah. A mikvah is a pool of naturally gathered water which conforms to a number of halachic requirements. The Geir will completely clean themselves and immerse themselves into the mikvah in the presence of a Beis Din. The immersion is done without clothes. There are obviously a number of modesty issues regarding this in regard to a female, and there are a number of approaches taken to ensure modesty.
When the Beis Hamikdosh stood Geirim would bring a Korban (sacrifice) but we cannot fulfill this mitzvah today. Rather we commit to doing so when the Beis Hamikdosh is rebuilt.
Jewish law requires respect for the Geir. It is forbidden to taunt them (Shemos 22:20, Vayikra 19:33). Even though we have a mitzvah to love all Jews, which includes the Geir, there is an additional mitzvah to love the Geir (Vayikra 19:34). A Geir is considered a Jew in all respects. He is legally speaking a new individual, separate from his non Jewish self. Torah commands all Jews to recite the following when bringing their tithes: "...bless Your people Israel and the ground You gave us, as You swore to our forefathers, a Land flowing with milk and honey" (Devarim 26:15). Even though the Geir was physically born to non-Jews, he is considered as a descendant of the forefathers of Israel. Because of this a convert's Hebrew name is ended as "ben(or bas) Avraham Avinu" , Son (or Daughter) of Abraham Our Father.
Many Jews today are not Orthodox and therefore do not consider Torah to be the inspired word of G-d given to Moshe at Sinai. However these people still have Jewish souls which urge them to serve the one true G-d in a Jewish manner. We therefore now see Reform an Conservative Judaism. I do not believe these represent the proper or true way to serve Hashem, but they are a testimony of how the Jewish soul want's to serve its Creator even when it doubts the traditional faith.
Members of these movements generally say they support those who wish to observe Orthodox Judaism. They recognize Orthodox Geirim as Jews. They therefore are troubled that Orthodox Jews will not recognize Reform or Conservative converts as Jews. They can only see this as intolerance.
However, there is nothing intolerant about it.
First, Orthodox Jews have nothing against Reform or Conservative converts. Many Orthodox Geirim originally converted by Reform or Conservative Rabbi's, moving to Orthodoxy as they learned more about Judaism. I have often spoken with people who have beliefs that would make them valid candidates to become an Orthodox Geir, but consider non Orthodox conversions because they do not live near an Orthodox community.
We do not accept non orthodox conversions as valid because they do not conform to traditional Jewish law. They are not preformed by a legitimate Beis Din because a court of Jewish law MUST accept Jewish law as valid (Doesn't it make since that for someone to give a DIN "Judgement" the must recognize the Law?). Some conversions are done without circumcision or mikvah. Many are done for improper motives.
If someone supports our right to Orthodoxy then they must support our right to not accept non Orthodox conversions. Orthodoxy means accepting the traditional laws as binding, and if one expects us to change our position about the laws of Geirus then one expects us to no longer be Orthodox. One cannot complain that we are intolerant and at the same time say implicitly that we do not have the right to exist.
It is also my understanding that the Conservative movement rejects Reform conversions if they do not include circumcision. Nor are Reform Rabbi's, as I understand, required to accept the such conversions. Furthermore, Reform and Conservative would not recognize a "Messianic Jewish" conversion regardless of Beis Din, circumcision, or mikvah because such an individual believes in Jesus. Is it not intolerant to draw this new line in the sand while challenging Orthodox for not changing the traditional expectations?