The following incident was raised as a contradiction to Rav Moshe Feinstein’s view that when it is obvious (anan sahadi) that the convert did not sincerely accept doing mitzvos that the conversion is null and void. It is not necessarily a contradiction. (The details were taken from Dr. Menachem Finkelstein’s Conversion Halacha and Practice page 621-626)
In Cairo 1908, a 22 year old Muslim desperately wanted to marry a certain beautiful Jewish woman . She refused unless he converted first. He gave a request in writing to the beis din. There was hatafas dam bris, and mikve as well as acceptance of doing mitzvos.
However immediately after the conversion he lived as a complete Muslim. Shortly after the conversion the couple married - with people upset since no one was aware of the conversion. The man then published an article in the paper stating.
since there are those who suspect that he converted and became a Jew and as such married a Jewess... but this is unthinkable and he would never do such a thing. He is a Muslim from birth and that each retained their religion when they married.
Immediately afterwards the following was established:
1) He had used a false name in his application to beis din
2) .His supporting document that he submitted to the beis din was forged and his references were not aware of what was stated in the document
3) He had revealed to two Jews that he was going through the conversion “to satisfy his desires with this beautiful women who had driven him mad” These two Jews had remained silent because they had been bribed.
4) After the wedding he continued to live amongst the Moslems as one of them. The couple had a son who he refused to allow to be circumcised and he was given the name of Muhammed. At this point the couple separated and the woman fled from her husband.
Two Egyptians rabbis who were consulted thought it possible to permit the woman to remarry without a get on the grounds that the conversion was worthless and thus there was no marriage. Rabbi Mas’ud Ben Shimon said, “If he had come in good faith at the time of the acceptance of the conversion without any deception, stratagems, and falsity then if he had reverted back to his previous religion he would still be considered a true convert. But since this was not the case since all was falsehood and deceit. Rabbi Aaron Cohen agreed with his reasoning that there was no conversion and thus no marriage and thus no need for a divorce.
While these two were waiting for approval by higher level rabbis, the husband was ordered by the kadi to divorce his wife in accordance with Islamic law and the government ordered him to pay his wife her kesubah.
The husband approached Rabbi Ben Shimon for help in avoiding paying the money. The rabbi told him to authorize him to give his wife a Get which Rabbi Ben Shimon and Rabbi Cohen promptly did.
The next question was the woman wanted to remarry and asked for a divorce certificate. The two rabbis were in a quandary because of the many doubts regarding this Get “ the likes of which might never have been” Therefore they decided to ask Rav Kook what to do. They sent him their rulings stating that the woman could remarry without a Get as well as a description of the Get they had given.
Rav Kook agreed to the appropriateness of asking for a Get. However he disagreed that the conversion was null due to fraud. He said that the acceptance of mitzvos was done properly. It didn’t matter what the man was thinking. Furthermore he saw no evidence that the man had intended to deceive or that he did not sincerely want to be a Jew. Rav Kook said the only problematic issue in the case was solely that he had converted for the sake of marriage - however bedieved the conversion was valid. Thus Rav Kook ruled that the conversion was good and the man had subsequently become a backsliding convert and that the Get was good.
The woman remarried on the basis of the Get and the conversion was not declared null and void – contrary to the written views of the first two rabbis. It seems that the first two wrote their views when they determined that the man would not give his wife a Get. In contrast Rav Kook wrote his views after the Get had been given.
It seems that there are three views in the literature. 1) Poskim who say that anyone who goes through the ceremony and declares before beis din that he will do the mitzvos, and has mila and tevila – even if subsequently he doesn’t keep anything is still a Jew. 2) There are others who say if it is obvious from the actions and statements that he never intended to be a religious Jew and was clearly insincere the conversion was never valid. 3) Finally there is a view that conversion is conditional on subsequently observing the mitzvos. If this condition is not met then the conversion is invalid.