The Rastafarian religion started in the slums of Jamaica in the 1920's and 30's. It is politically base. Some Rastafarians see it as a way of life and some as a religion. There is no formal structure and beliefs vary widely. You can learn more at Religion Facts/Rastafarianism
Zephaniah is a performance poet (poetry is composed for or during a specific performance). He is also a reggae artist. He left school at 13 unable to read or write - he was dyslexic so that probably played a part in his inabilities and leaving school.
He describes his poetry as being based on 'street politics' based in Jamaica. He published his first book of poetry in 1980 called Pen Rhythm
He has received many honorary doctorates from many prestigious universities. Zephaniah has also written a few novels and several children's books.
To read about Benjamin Zephaniah here is an interview with Writers and Artists, The Insider Guide to Media.
Information gathered from Wikipedia and PoemHunter.com Each of the links go to the page about the author.