RUSTENBURG, South Africa, Aug 21 (Reuters) - Its leaders call themselves devout Christians and say life is sacred. But its supporters march with spears, machetes and clubs and anoint themselves with magic potions to ward off police bullets.

By taking on South Africa's powerful mining houses and the politically-connected NUM mineworkers' union, breakaway union AMCU has put itself at the heart of national soul-searching after Thursday's police shooting of 34 striking platinum miners at a mine northwest of Johannesburg.