Rabbi Dov Linzer of YCT and the de facto head of the Open Orthodox movement concludes and agrees with Rav Moshe Feinstein - that a person who converts for the sake of marriage to a non-observant Jew is not a convert at all - l'chatchila!

Accepting the Mitzvot as a Convert: Does it Matter What You’re Really Thinking?

 

by Rabbi Dov Linzer  - (Head of the Open Orthodox movement in the U.S.A., the equivalent of the  "Radical Left" of Jewish political movements --- Yet, he concludes and agrees with Rav Moshe Feinstein - that a person who converts for the sake of marriage to a non-observant Jew is not a convert at all - l'chatchila. Please click on the link below the post to see his intriguing Halachic sources)

Rabbi Yitzchak Yehuda Shmelkes (1828-1904) was one of the leading rabbis in the latter part of the 19th century in Eastern Europe. He was the head of the rabbinical court in Lvov (Lemberg) from 1869-1893. His Beit Yiẓḥak (6 vols., 1875–1908), on the four parts of the Shulkḥan Arukh, was widely acclaimed. His opinion on halakhic questions was sought by many prominent contemporary scholars.

Rabbi Schmelkes made a number of particularly influential rulings in new areas of Jewish law. Regarding copyrights, he argued that an author’s exclusive right to publish their manuscript derived from the Jewish law of unfair competition and the author’s property right in controlling access to the physical manuscript, a position held by many contemporary authorities in halakhic copyright law.

 Rabbi Shmelkes also dealt with the question of the use of electricity, other than electric lights, on Shabbat.  He ruled that one could apply the category of molid, creating something new, to the generating of electric current.  This position was widely adopted for many years, although recently it has been challenged by a number of contemporary poskim.

In the current teshuvah, Rabbi Shmelkes deals with a case of conversion for the sake of marriage where it is highly questionable if the prospective convert really intends to live an observant life.  Rabbi Shmelkes first rules in line with the Talmud and against certain other poskim of his time, that conversion for the sake of marriage is prohibited li’chatchilah.

The part that we have excerpted below focuses on his analysis regarding whether such a conversion works post facto.  The Talmud states that it does, but Rabbi Shmelkes questions whether this would apply even in cases where we know that the person is not sincerely accepting upon him- or herself the obligation to observe the mitzvot.  This question – what level of commitment of observance is required, and whether we need to concern ourselves about the person’s intentions or not, especially if as far as we can tell the person is, or may be, sincere – is one that is highly relevant today.

We have chosen this teshuvah for Shavuot, because of its connection both to the book of Ruth and to receiving the Torah at Mt. Sinai.  In the Talmud, Ruth is seen as a paradigm for the righteous convert, one who sincerely commits to all the mitzvot, and who is not doing it for any ulterior motive (although, interestingly, her conversion seems to be motivated more from a love of Naomi than from a connection to the faith itself).  And the acceptance of the Torah and mitzvot at Mt. Sinai serves, in the Talmud, as a model for the various rituals of conversion (immersion, circumcision, and acceptance of mitzvot).

Rabbi Shmelkes draws on the Mt. Sinai example and the various midrashim that deal with the idea that the Israelites were coerced to accept the Torah, and raises questions as to whether we can derive from these midrashim that a verbal acceptance suffices even if a person’s commitment is not fully sincere.  He goes back and forth on this question, and although he seems at times to conclude decisively that a verbal commitment is not sufficient if we know or suspect that the person is not sincere, in the end he is prepared to recognize the conversion under discussion, at least post facto. In the end, the question remains: Does it suffice to say, as our foremothers and forefathers did at Mt. Sinai, “We will do and we will hear,” even if their hearts were not fully in it, or must we all have the sincerity and depth of commitment as Ruth did when she said to Naomi, “You nation is my nation, and your God is my God”?

In conclusion – behold, were your honor to permit this Gentile woman, who had intercourse with a Jew, to convert, and to allow this Jew to marry her, this is something that is not possible for two reasons. One, that as a matter of halakha, even were she have to already converted, it would be forbidden to marry her, as is stated in the Mishna and Tosefta, And two, if this Gentile wishes to convert for the sake of some benefit, i.e., for the sake of marriage, one should not agree to convert her li’chatchilah. However, were she to convert in the presence of three non-scholars who did not know that she was doing this for the sake of marriage, then post facto the conversion would be valid, and were he (her lover) to marry her, he would not be obligated to divorce her.  Speaking more generally, when it comes to converts nowadays, one needs to see that accept upon themselves, sincerely, to observe the foundations of faith and the rest of the mitzvot.  And Shabbat is a major foundation, for one who violates Shabbat is like one who worships idols.  And if a person converts himself and does not accept upon himself the observance of Shabbat and the mitzvot, he is not a convert.
I have written what appears to me in my humble opinion. 

https://library.yctorah.org/lindenbaum/accepting-the-mitzvot-as-a-convert-does-it-matter-what-youre-really-thinking/