Harper sweetens the pill of his undoubtedly stern personal, political and religious homilies with beautifully weighted musical settings and a canny awareness that we haven't turned up a for an evening of collective hand-wringing.
He's careful not to overegg his pious pudding - this prophet rocks. Harper's spiritual militancy also finds a natural home in his more forthright protest songs, in particular "Fight for your Mind" and "People Lead". It doesn't take an impressively faithful "Voodoo Child" to realise that the bluesy rock of the Jimi Hendrix Experience inspires the powerful articulation of his band, the innocent Criminals.
Here too, though, as in the storming "Like a King" (where Bob Marley's eloquent indignation surfaces in Harper's response to the beating of Rodney King and the LA riots), Harper gets surprising mileage from some pretty obtuse refrains. With the requisite black consciousness inflections (Black Panther clenched fists, unflinching grimace), a funky Rastafarian T-shirt and lyrics as, well, let's say "roomy" as: "Some people believe, I some people know, I Some people deceive, I Some people show", somehow achieve a universal significance.
That may be the key to his success: his masterful absorption of the political and blues histories of black music. On this evidence at least, he seems to be the true heir to the soulful rock and R&B of Jimi Hendrix and Prince.
It's difficult to nominate any serious competition, save the mere pretender Lenny Kravitz. Harper wears his heritage lightly. Marvin Gaye, Cat Stevens, Aaron Neville, Sly and Stone hang in Harper's crisp voice all evening, defying the ship's funnel acoustics of the Empire.
Come evening's end, the angelic Harper and his compelling millennial blues have the audience singing a funky a cappella gospel to itself, resolving to "rise and shake off the shackles of history". In the Church of the House of Harper, anything seems possible.