Matthew 12:34,35 -- ....."For out of the fullness (the overflow, the superabundance) of the heart the mouth speaks. The good man from his inner good treasure flings forth good things, and the evil man out of his inner evil storehouse flings forth evil things.
Words won't work without faith any more than faith will work without words! It takes them both to put the law of faith in motion.
As Matthew 12:34-35 says, it's the words that come from the heart that produce results. The person who just throws in a couple of faith words now and then isn't speaking them from the abundance of his heart, so they're not effective.
Does that mean you shouldn't start speaking words of faith until you're sure you have the faith to back them?
No! Speaking words of faith is good spiritual exercise. If you want to receive healing by faith, for example, fasten your mind and your mouth on the Word of God where your health is concerned. Instead of talking about how miserable you feel, quote Isaiah 53:5. Say, "Jesus was wounded for my transgressions. He was bruised for my iniquities. The chastisement of my peace was upon Him; and with His stripes, praise God, I was healed!"
If you'll continue to meditate on those words and continue to say them, the truth in them will begin to sink in. They'll take root in your heart (spirit) and begin to grow. And eventually you really will be speaking from the abundance of your heart (spirit).
When that happens, it won't matter what the circumstances look like. You'll know you have what you've been believing for and the devil himself won't be able to talk you out of it. You'll cross the line from hope to faith, and you'll start seeing those mountains move.