"You have to put yourself in a situation wherein all you have is God and His promises that if He does not deliver on what He said you are sunk." That's what one said when asked as to why he was leaving the United States for Africa. At least that was one of his reasons.
Let's apply what he said to saving faith --- You know, saving faith is like that. Saving faith is depositing and entrusting your self and your eternal welfare on what Christ did on the cross that if what Christ did on the cross was really worth nothing then you are sunk. But, the good thing is this --- you know that it was not worth nothing. You know that it was worth everything to God for the sinner's salvation.