Ilya Somin at The Volokh Conspiracy has some interesting observations about interracial dating. It turns out that there's more resistance to interracial dating even when it comes to online dating, which means it doesn't just have to do with who you associate with in daily life within your local community (although that's got to be a factor, because groups who tend to live in areas where they are the majority are less likely to take part in interracial dating than groups that typically find themselves in the majority wherever they live).
One factor that he includes that I hadn't connected with this is that people with higher or more specific standards in non-racial ways might be more open to interracial dating simply because their pool is already much smaller than other people's. He includes religious standards such as refusal to date someone of another religion. This may well be one explanation why, in my own observation, evangelical Christians (at least in the circles I run in) are far more open to interracial dating than most any other group I can think of. It may well be partly because evangelicals have a smaller pool to pick from because many evangelicals will date only other evangelicals, and being open to interracial dating helps widen the pool from what it would be if they looked only at people within their own racial group.
Nonetheless, I don't think such an explanation undermines what I've long thought to be the explanation for evangelicals' greater openness to interracial dating. I've generally taken it to be because evangelicals have a heightened sense of the oneness of all genuine followers of Jesus, who evangelicals typically see as including mainly those who have put their allegiance to Christ above all other allegiances. Identity in Christ is primary, and other sources of identity are at best secondary. Thus when I think about who I'm most closely aligned with, I'm going to think of black evangelicals as much closer to the heart of my identity than I will white non-believers.
This isn't just not in conflict with Somin's point, as if they are two compatible explanations. It's actually the same fact under two different descriptions. On the one hand, evangelicals who have this restriction do indeed have a smaller pool to pick from, and they are thus more likely to be willing to include others in the pool than just those of their own race. But the philosophical justification for restricting the pool to like-minded believers is the same justification for expanding it to include like-minded believers regardless of race. After all, it's the sense of closer identity with fellow believers that leads both to the restriction to only believers and to openness to believers of other races.