Consider this example. My father just passed away. He owned a fishing boat. My mother wants to give me my father’s fishing boat. She has promised me the boat. Let’s suppose I go over in a couple of months to get the boat. After I get there she laughs and says, “Oh, I was just kidding, you cannot have the boat.” I make my trip to Louisiana based upon the promise that she has given me the boat. My faith would be based on my mother’s promise.
From Leland Patrick’s Sermon: Understanding Faith