Very briefly, the Law of Return was a basic law passed, really, at the establishment of the state in 1948. It was done partly as a way of reflecting the experience that Jews had in Europe. They codified those categories of individuals who would be entitled to automatic citizenship, if they applied, by virtue of being Jewish. They used the same set of criteria that the Nazis had used in reverse, identifying who was a Jew for the purposes of selecting them out for what turned out to be the Holocaust.
However, while it's a right, it's not an obligation. For example, I'm a Canadian-born, Montreal-born Jew. I've been to Israel more than a few times in my life. I carry a Canadian passport because I was born in Canada. I do not carry an Israeli passport. I'm not a citizen of Israel, because I haven't made application to be a citizen of Israel. So there are no circumstances under which I as a Jew, as a Canadian citizen, could have my citizenship revoked by virtue of being a national of another country, be it Israel or any other country.