(Joseph Mathunjwa addresses members of the mining community during a strike at Lonmin’s Marikana platinum mine in Rustenburg, 100 km (62 miles) northwest of Johannesburg, May 15, 2013. REUTERS/Siphiwe Sibeko)

The 48-year-old son of a Salvation Army preacher has won tens of thousands of followers portraying himself as a Christian soldier fighting for South Africa’s downtrodden miners.

“I was chosen by the plight and the suffering of the working class in South Africa,” Joseph Mathunjwa, president of the Association of Mineworkers and Construction Union (AMCU), told workers last month from Lonmin’s Marikana platinum mine, site of a demonstration last August where police shot dead 34 wildcat strikers.

AMCU’s emergence as the main labour force in South Africa’s platinum belt – home to 80 percent of the world’s known reserves of the metal – is an unprecedented grassroots challenge for President Jacob Zuma’s ruling African National Congress (ANC).

The labour unrest in South Africa’s mines last year cost platinum and gold producers billions of rand in lost output, resulting in sovereign credit downgrades. Fears of more turmoil in the mines as workers, unions and companies square off for a new wage bargaining round have helped drive the rand to four-year lows in the last month.