What major religion opposed interracial marriage in the time frame to which you refer alfteich? And what is the public policy reason to oppose interracial marriage other than just racism? As to SSM marriage, some believe, for reasons not empirically based, but sometimes for reasons of genuine confusion about cause and effect, that SSM would have a collateral deleterious effect on society, such as undermining the institution of marriage, getting it away from procreation, and so forth, all wrong headed ideas, but not per se grounded on hatred, bigotry and prejudice.
It does not matter how big or small a religion is. If you consider religious justification for opposition a mitigating factor, then it need not matter how big the opposition is. It can also be a personal religious view without attachment to a church body. You say yourself that the reasons for opposing SSM are often not empirically based. The fact that there is over 100 years worth of collective data across several decades now, in terms of recognition of SSM in jurisidictions across the world and corresponding social data/trends means nothing to these people. But in formulating both public policy and good business practice, it
should matter. Is being uncomfortable with certain people having access to rights a fair reason to accommodate that in public policy?
You say that opposition to interracial marriage is 'just racist'. Of course, hindsight is a wonderful thing. Given that only a small minority (though still about 15% in the USA according to Gallup) oppose interracial marriage and no one is trying to win souls or votes in opposing it, it is very very easy to say that without repercussion. Things become simply 'obvious' in time. A significant number of influential political organisations and religious organisations that move against SSM either concurrently, or have in the past, opposed
all LGBT rights, so you can conclude, despite their protestations, that their opposition to SSM is 'just homophobic'
But let's rewind back to 1995. It's basically pre-internet which makes things harder, but studies such as the National Survey of Population growth were misused to demonstrate that interracial marriages ended earlier than other marriages; younger marriages, higher divorce rates (50% higher), decreased family stability and so on. The study linked to a significant number of studies that agreed with that assertion, conducted in the 1960's that are now buried in the 'what the f-ck were we trying to prove' annals of social sciences. Was there a mainstream movement to oppose interracial marriage once the Supreme Court had decided? No, but if there was, you can be assured that those who opposed it would be appealing to 'statistics' and unsubstantiated claims of instability and therefore dismissing the integrity of such marriages from the get go.