Rabbi Melamed wrote an excellent explanation of the Jewish view of conversion...
Here it is from :
http://www.israelnationalnews.com/News/News.aspx/138668
A Definitive Essay on the Laws of Conversion to Judaism
Av 8, 5770, 19 July 10 10:31
by Rabbi Eliezer Melamed(Israelnationalnews.com) Judaism's Positive Approach to Converts
The laws relating to Jewish converts are among the most astounding laws in the Torah. The Torah (Bible) teaches us clearly that any non-Jew who truly seeks to join the Jewish people may do so according to Jewish law, putting the lie to those who have called the Jewish people or their laws racist.
The Nazis ruled out the possibility of joining the Aryan “race." Jews who had converted to Christianity were viewed as Jewish in the eyes of the racist Nazis. This, however, is not the way of Judaism. In fact, if a German or an Arab should seek to join the Jewish People, even if he is the son of a fierce anti-Semite, he is accepted. Moreover, we are to love him more than other Jews, in keeping with the commandment to “love the convert, for you too were strangers in the land of Egypt" (Deuteronomy 10:19).
Relating to Converts
After a person converts to Judaism, he is like any other Jew. One must be more sensitive to his feelings than those of other Jews because of the extreme difficulties that he faces. It is not easy to leave one's people and one's home in order to join a nation with an ancient culture, shared history and rich tradition which is not easily absorbed even after many years of study.
This explains why Jewish Law rules that whoever grieves the convert transgresses three Biblical prohibitions (Baba Metzia 59b). First, it is written “Do not grieve one another” (Leviticus 25:17), which applies to all Jews, including the convert. Then the Torah adds two more specific laws against grieving the convert: “You shall not wrong a stranger, nor oppress him; for you were strangers in the land of Egypt” (Exodus 22:20), and “If a stranger sojourns with you in your land, you shall not wrong him. But the stranger who dwells with you shall be to you as one born among you, and you shall love him as yourself…” (Leviticus 19:33-34).
We are twice commanded to love the convert (Rambam, Hilchot Deot 6:4). Firstly, we must love the convert like any other Jew, as it is written, "Love your fellow as yourself” (Leviticus 19:18). And again, regarding the convert in particular, it is written, "Love the stranger, for you were strangers in the land of Egypt" (Deuteronomy 10:19).
The A-lmighty Himself loves the convert, as it is written, “He loves the convert to give him food and clothing” (Deuteronomy 10:18).
Conversion
Jewish law's attitude to conversion appears contradictory at first glance. There is enormous respect and love for the convert who has left his people in order to join the Jewish people; on the other hand, there is an attempt to dissuade him from converting.
Howver, the reason that Judaism seeks to dissuade the convert is in order to be certain he sincerely wishes to join the Jewish people and that this is not just a passing phase.
The Code of Jewish Law, Shulchan Aruch, rules (Yoreh Deah 268:2) that when a non-Jew comes before a rabbi and requests to convert, the rabbi must say to him: “Why do you want to convert? Don't you realize how much the Jewish people suffer in this world? … Even today there is much anti-Semitism in the world, and many Muslims wish to do away with us. And all of this is because we are Jewish. So why do you want to join our suffering nation? … A non-Jew can also be righteous and can even reach a level of divine inspiration.” If at this point the non-Jew changes his mind about converting, that is fine.
However, if he says, “Despite this, I desire to join you,” he is immediately accepted, and the second stage of the conversion process begins. He is taught the fundamentals of Jewish faith, the prohibition against idolatry, and a number of other laws. Then he is told, “You should know that so long as you are not Jewish, it is permissible for you to labor on the Sabbath and to eat pork or other non-kosher animals. When you convert, however, all of these things become forbidden, and if you violate the Torah you will be punished.” If he agrees and accepts this upon himself, he is converted.
How Much Must the Convert Learn Before Conversion?
There is no need to teach a prospective convert the entire Torah. It is sufficient to teach him some of its foundations, and if he accepts them, he can convert, according to Shulchan Aruch (Yoreh Deah 268:2), which states: “He is taught some of the minor commandments and some of the major commandments, and he is taught some of the punishments for violating the commandments,” but, “we do not overburden him and we are not overly strict with him.”
The Essence of the Conversion
The essence of converting to Judaism is to accept commitment to the Torah and the commandments before a rabbinic court. The prospective convert is taught the fundamentals, and if he demonstrates a willingness to accept the rest, he is converted immediately, and thereafter continues to study and grow as a Jew.
This practice has its source in a number of Talmudic anecdotes, the most famous one being the following from Tr. Shabbat 31a:
A non-Jew once came before Shammai the Elder and said to him, “I wish to convert, but I will only do so on the condition that you teach me the entire Torah while I stand on one foot.” Shammai pushed him away, reasoning that it is impossible to teach a person the entire Torah on one foot. But the same individual came before Hillel the Elder, and Hillel agreed to convert him, telling him, “That which is undesirable to you, do not do to your fellow. This is the entire Torah, the rest is all commentary.”
In other words, the idea that a person should not do to others that which he himself finds undesirable is the central idea of the Torah. Since there are many precepts that do not seem to be connected with this idea, it follows that in order to understand Hillel’s words, the convert must continue studying.
Yet the law says that if a non-Jew is not ready to accept upon himself all of the commandments, it is forbidden to convert him. How, then, did Hillel convert this non-Jew who only knew about loving your fellow man?
Hillel understood that this non-Jew had pure intentions, but lacked knowledge. He was certain that when it came down to it, he would continue to learn Torah and fulfill all of the commandments (Tosafot, Yevamot 109b). From here we learn that it is unnecessary to learn all of the Torah's laws before converting; it is sufficient that the rabbinic court reach the conclusion that the convert earnestly intends to join the Jewish people and accept upon himself the yoke of the Torah (Beit Yosef 268, end).
However, if the rabbinic court accepts someone who does not intend to keep the commandments to begin with, this will cause great damage to the Jewish people, and in this regard the Sages said (Yevamot 109b): “Evil will come upon those who accept [insincere] converts.”
Conversion in Practice
In sum, two matters must be clarified by the rabbinic court before it can accept a convert: 1) Does the convert harbor ulterior motives? 2) Is the convert ready to accept the Torah and its commandments?
When it is clear that the convert is sincere on both counts, the main part of the conversion process is complete, and the rabbinic court proceeds to the practical aspects of conversion. Just as the Jewish people entered a covenant with the A-lmighty by way of three acts - circumcision, ritual immersion, and sacrifice - so must the non-Jew who seeks to join us enter the covenant of the Jewish people via circumcision for men, ritual immersion, and sacrifice.
As the Holy Temple does not exist today, conversion does not include sacrifice. However, regarding circumcision and ritual immersion, one who has not carried out these two acts is not a convert.
Accepting the Commandments
No other nation in the world possesses a concept resembling Jewish conversion. Many countries grant citizenship to immigrants, parallel to the idea of a 'ger toshav' in Jewish law. A 'ger toshav' is a non-Jew who is permitted to live in the land of Israel on the condition that he keeps the Seven Noahide Laws and accepts Jewish sovereignty over the Land of Israel.
An Italian who receives American citizenship remains Italian as well, but a convert to Judaism becomes Jewish in all respects - not only as far as citizens' rights are concerned, but also as far as absolute national belonging.
Therefore, the foremost condition of conversion is that the convert accept upon himself the Torah. The Torah is essentially an expression of the national character of the Jewish people. The spirit of the Torah and the spirit of the nation are one. Just as the Jewish people became a nation by accepting the Torah at Mount Sinai, so must one who wishes to join the Jewish people accept upon himself the Torah as an individual before a rabbinic court.
However, if after the rabbinic court becomes convinced that the convert's intentions are pure and converts him, the convert begins to neglect the Torah, he continues to be considered Jewish. Just as a Jew who does not yet observe all of the commandments of the Torah is nonetheless considered Jewish, so too, a convert who subsequently neglects the Torah remains Jewish.
Defining the Acceptance of the Commandments
As noted above, there is no need to teach a prospective convert all of the complexities of the law. He is taught the essentials, beginning with commandments relating to Jewish faith, and the prohibition of idolatry, then commandments teaching one how to behave toward others, and then the fundamental laws relating to the Sabbath, family purity, and kosher food.
What if the convert is prepared in principle to accept the Torah commandments, but believes that now and then he will have to transgress some of the commandments?
The eminent Rabbi Chaim Ozer Grodinski (“The Achiezer”) holds that it is possible to convert such a person. This is because we relate to the acceptance of commandments in principle. In principle, the convert has agreed to take upon himself observance of the commandments, and it is only on occasion that he believes he will transgress.
Although there are important authorities who disagree with this opinion, in practice, many follow the ruling of Rabbi Grodinski, and if it is clear to the rabbinic court that the convert accepts the commandments in principle, it is possible to convert him.
A Reform or Conservative "conversion" is not valid at all because the convert in principle does not accept all of the commandments.