A conversation took place between the leader and scholar, Ja'far as-Saadiq and an avowed atheist.  Ja'far asked the  person:

"Have you ever travelled on the sea?"
"Yes."
"Have you experienced its terrors?"
"Yes, indeed!  One day while we were out at sea, a terrible hurricane blew up and smashed our ship.  Several sailors perished.  I clung to a rafter of the ship but it was soon snatched away.  I was thrown about in the stormy sea but eventually was tossed up on the sore."
"When the storm broke," Ja'far commented, "perhaps you first relied on the ship and the sailors for your safety and then  on the rafter which saved you for a while.  But when all these  went, did you resign yourself to death or did you still hope for safety?"
"I hoped for safety."
"On whom did you hope for safety?"
The man was silent and Ja'far said:
"The Creator is the one on whom you placed your hopes at that time.  And He is the one who delivered you from drowning."

After this conversation, the atheist was no longer an atheist.