Believe and receive

Matthew 21-21

Jesus said "I tell you the truth, if you have faith, and do not doubt, you can say to the mountains `Go throw yourself in the sea' and it will be done."

(he also kills a fig tree, but that's not as impressive)

"If you believe, you will recieve whatever you ask for in prayer."

The message is quite simple here - "Believe and receive. Doubt and do without."