When presidential candidate Mike Huckabee said during the Republican primaries that he was comfortable speaking the language of Zion, he clearly referred to the social and, to some degree, theological contexts of conservative evangelical Protestants. I've long sensed that Obama speaks in the cadence of Zion, one that seems familiar to any ears familiar with black churches.
Linguist John McWhorter has helped explain this sound in a wonderful brief essay for The New Republic:
Black English is a matter not just of slang, but of sentence structure and sound (why you can tell most black people's race over the phone, which is proven in studies). Some blacks use all three; Obama is one of the many who wields mostly the sound. Listen to the way he often ends sentences on a higher pitch than, say, Tom Brokaw would, with that preacherly hang-in-the-air. Or the way he often pronounces "history" as "historih," "ability" as "abilitih." His rendition of the word responsibility was indicative: with a cadence typical of Black English, capped by a final "ih." No President has ever intoned sentences in this way, because they were not black.
Contrary to the fabulistic notion that gets around here and there that Black English is an African grammar with English words, the sentence structure is basically a blend of regional British dialects that slaves heard from their masters and the indentured servants you learned about in grade school. The sound, however, is partly a legacy of the African languages the slaves spoke. Especially, the melodic quality of Black English, heightened in sermons and speeches, is a legacy of the fact that in many African languages, pitch is as important in conveying what words mean as accent. In the way he said responsibility, he was using language in a way that is warp and woof of the grammar of, for example, his father's native language Luo.
... It is certainly part of why Obama was elected. Imagine John Kerry or even either Clinton trying to get elected intoning "Yes, we can!" What made that seem prophetic, or even plausible, from Obama was that it was couched in a Black English intonation -- partly church, maybe even a dash of street (a cousin of mine likes that Obama "has a bit of the ghetto in him"). This aspect of Obama's oratory got to as many whites as blacks. "He's just ..., he's just, oh, he's just ...!" white Obama fans would often exclaim as the Obamenon set in, grasping at the mot juste. Many of them had basically been to their first black church service. He was just ... well, black.
Barack Obama's portrait is from Wikimedia Commons.