thorne,
I haven't the slightest idea why anyone would voluntarily convert to ANY religion

the reason is some religions require both spouses to be of the same religion, so if they want to get married some spouses be it the female or the male may be required by that relgion to convert before marriage so the marriage is recongnized, example i believefor example that if a person is of say Muslim up brining, theirreligion may require a person to convert from say christianty or jewdism to Islam for the purposee of marriage, or even coonvert from a reformed version of the same religion to orthodox of the same
I am not defending any 1 religion, but an Orthodox Jew MUST marry and Orthosed Jew and not one who is of Reformed Jewdism

Similar to Catholosism, unlike most religions I have heard about, if you are catholic and wish to marry a cathilic you must go through church mandated cousling before the church wil regonize the union even if both spouses are Catholic