From how I read I understood the following.
The life lived to express the commission made from above. Bill's life will prove that God is obligated to do whatever He Has promised nonmatter the fact that man tries to dodge/being disobedient, like Jonah. His life also expresses the cost of being disobedient to your call from God. It also expresses the restoration that God can do like Job. Then after all it gives a clear picture to the believer, that William Branham was a true prophet sent by God.