For some related sources, see the subject of Anusim on Wikipedia, specifically, and especially, the short section on Rabbinic Legal Opinions, here: http://en.wikipedia.org/wiki/Anusim#Rabbinic_legal_opinions
"Hakham Se‘adyá ben Maimón ibn Danan, one of the most respected Sephardic Sages after the Expulsion, in the 15th century stated:
Indeed, when it comes to lineage, all the people of Israel are brethren. We are all the sons of one father, the rebels (reshaim) and criminals, the heretics (meshumadim) and forced ones (anusim), and the proselytes (gerim) who are attached to the house of Jacob. All these are Israelites. Even if they left God or denied Him, or violated His Law, the yoke of that Law is still upon their shoulders and will never be removed from them.
Hakham BenSión Uziel, the Chief Sephardic Rabbi of the State of Israel, stated in mid-20th c.
And we still have to clarify on the (subject of) Anusím, to whom the government forbids them to perform Halakhicly valid marriages, if it's necessary to say that their wives must have a Get to permit them (to marry another man), for the reason that, by force of the Law (Hazaqáh), a man does not have intercourse for promiscuity (zenút). . . (In our very case), we deal with those who converted and kept Torah in secrecy and hide their religion because of the gentile surveillance, we say that they do have intercourse for the sake of marriage.
It follows that Hakham Uziel considered anusím as Jews, because only Jews can give or receive a Get, a Jewish divorce.
Rabbi Moshe ben Maimon (Maimonides) stated in the Mishneh Torah Sefer Shofetím, Hilekhót Mumarím 3:3
But their children and grandchildren [of Jewish rebels], who, misguided by their parents . . . and trained in their views, are like children taken captive by the gentiles and raised in their laws and customs (weghidelúhu haGoyím `al dathám), whose status is that of an ’anús [one who abjures Jewish law under duress], who, although he later learns that he is a Jew, meets Jews, observes them practice their laws, is nevertheless to be regarded as an ’anús, since he was reared in the erroneous ways of his parents . . . Therefore efforts should be made to bring them back in repentance (LeFikakh rawí leHah zirán biTeshubáh), to draw them near by friendly relations, so that they may return to the strength-giving source, i.e., the Toráh "