At the moment many Americans find him a bit of an enigma: a flip-flopper on some big issues, wooden in public, and a committed member of one of the world's odder religions.
And the truer, politically radical image of Bob Marley is interwoven with his own standing as the prophet of Rastafarianism, that odd, amorphous religion that could perhaps only have emerged from the mysterious island of Jamaica, whose permanent ganja fumes permeate the creed's unwritten philosophy.
There's only so much to be said about the odd rectangle of religion, birth control, sexually transmitted disease and war.
It seems unlikely, but with religion odd things do happen such as the Christian revival that began a century ago in a Los Angeles warehouse, when people suddenly began falling into one another's arms and speaking in strange tongues.
Over the faces, and throughout the composition, the artist paints eclipsing or crescent moons, which, when combined with the sacrificial look of the subject, suggest an odd combination of religion and science.
It goes without saying, too, that any contemporary geo-political resonances are stuffed well out of sight: despite the odd mention of religion here and there, there's no concession to the fact that this is notionally set in the US's bete noire, Iran.
As Gary Forsythe writes in his book, Time in Roman Religion, odd numbers were perceived as more auspicious than even ones because such numbers could not be divided.
Roper, for his part, finds this description odd, saying, "I think religion is for all genders".
Most recently, he's been behind BBC2's QI, reflecting his own curiosity about science, religion the odd phenomena that make up our world.
Although it might seem like an odd way to mix religion and politics, Taoism often deifies famous people; at least three Taoist temples in one part of China are dedicated to Chairman Mao.
