Memory
On two separate occasions Jesus fed thousands of people by multiplying bread and fish. He made so much extra food that everyone had as much as they wanted, and there was still some left over.
On both of these instances, the disciples questioned where the bread would come from. And in both cases, Jesus provided.
Shortly after the second instance of Jesus feeding the thousands, the disciples were in a boat crossing a nearby lake when they noticed they only brought one loaf of bread.
Jesus warned them about the leaven of the Pharisees and of Herod.
Then the disciples began to argue about the fact they didn’t have any bread.
All this right after Jesus had multiplied a small amount of bread to feed thousands of people.
Ridiculous.
Jesus was finally fed up with them and spat off a slew of open-ended questions.
Why are you arguing about having no bread? Don’t you know or understand yet? Are your hearts too hard to take it in? You have eyes–can’t you see? You have ears–can’t you hear? Don’t you remember anything at all? . . .
Sometimes all it takes to have faith in what Christ can do is a little bit of remembrance of what He has done in the past.