I think that there is a religious element to Mandela's life and work. It is secondary to the leader element and his commitment to the African National Congress (ANC). The political struggle in which Mandela lived his life was something that he assigned primacy to in his work and in his public image. He was fairly direct in making his cause, his work, and the means of communicating both something tht resided in the realm of politics and in the realm of policy making. Religion did not enter into it. Mandela's first marriage struggled, in part, because his first wife was a Jeovah's Witness, a religion that precluded political affiliation. It is here where I think that one can see where religious expression was secondary to the political struggle that shaped Mandela's life.
One has to consider that in the darkness of Robben Island and in the pain of his imprisonment, his religious faith helped him endure the unspeakable conditions that he had to endure. Archbishop Desmond Tutu has alluded to this, speaking to Mandela's reservoir or "compassion" that is motivated by his Christian faith. Consider Archbishop's words that speak further to this point:
...I mean a lot of his people said that [Mandela] would have won over many others if, at that particular point, he had made some reference to God. And we should respect the fact that he refused to manipulate religion in that kind of way... But I think he does have a great deal of inner resources, and that 27 years was partly responsible.