Gallup:

Only 31% of black Democrats in America say homosexual relations are morally acceptable, roughly the same as the 30% of Republicans who agree, while very much different from the 61% of nonblack Democrats who say homosexual relations are morally acceptable....

Just 30% of black Democrats say they would agree that marriages between same-sex couples should be recognized by law as valid, compared to 57% of nonblack Democrats. Black Democrats are not quite as conservative on this policy issue as Republicans (among whom just 22% favor legalization of same-sex marriage), but are closer to Republican attitudes than to nonblack Democratic attitudes. And, as noted at the beginning of this story, black Democrats' views on the moral acceptability of homosexual relations are almost identical to those of Republicans, and the attitudes of both blacks and Republicans are significantly different from the attitudes of nonblack Democrats on this issue.

One of the underlying explanations for the divergence between the views of black and nonblack Democrats on these moral issues is religion. Black Democrats are much more religious than nonblack Democrats, and religion is highly related to views on homosexual relations.