A white person was not allowed to date a black person. There was no conversion option. It didn't matter whether both were Baptists or one was Bahai and one was Hindu. Some Jews oppose intermarriage more out of a sense of tribal loyalty than out of love for their religion. Yet even that chauvinistic position, though possibly less valid than the objection to intermarriage on religious grounds, is more valid than Bob Jones University's ban on interracial dating.
Racism looks outward with horror.
Its efforts are directed at preventing possible infection by the other. Racists frown on what they view as miscegenation because they hate blacks, Indians, Jews, the Irish, and so on. Tribalism, by contrast, looks inward with worried concern. The primary concern of Jews, as with other ethnic minorities, is maintaining the survival of their own group, not keeping out others. The proof of this is the existence and common use of conversion rituals.