The path was painted to look like the far wall from the perspective of the leaping point. That was the entire point of the camera move that went back and forth to show this. If it was God, the filmmakers would have shown fairy dust or whatever making it appear and disappear. Indy throws gravel on it so it will be visible for the next person (who will now not need to make a leap of faith). Could a handful of gravel undo God's intended requirement for entry?